wip: merge main in

7 files changed, 636 insertions, 598 deletions

diff --git a/src/client/layout.rs b/src/client/layout.rs
index 2d1daaf4..e82f9045 100644
--- a/src/client/layout.rs
+++ b/src/client/layout.rs
@@ -1,6 +1,5 @@
-use directories_next::ProjectDirs;
 use serde::{Deserialize, Serialize};
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::{fs::File, io::prelude::*};
 
 use crate::panes::PositionAndSize;
@@ -177,16 +176,12 @@ pub struct Layout {
     pub split_size: Option<SplitSize>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub plugin: Option<PathBuf>,
-    #[serde(default)]
-    pub expansion_boundary: bool,
 }
 
 impl Layout {
-    pub fn new(layout_path: PathBuf) -> Self {
-        let project_dirs = ProjectDirs::from("org", "Zellij Contributors", "Zellij").unwrap();
-        let layout_dir = project_dirs.data_dir().join("layouts/");
+    pub fn new(layout_path: &Path, data_dir: &Path) -> Self {
+        let layout_dir = data_dir.join("layouts/");
         let mut layout_file = File::open(&layout_path)
-            .or_else(|_| File::open(&layout_path.with_extension("yaml")))
             .or_else(|_| File::open(&layout_dir.join(&layout_path).with_extension("yaml")))
             .unwrap_or_else(|_| panic!("cannot find layout {}", &layout_path.display()));
 
diff --git a/src/client/pane_resizer.rs b/src/client/pane_resizer.rs
index 007dc33f..f9ec71b8 100644
--- a/src/client/pane_resizer.rs
+++ b/src/client/pane_resizer.rs
@@ -1,7 +1,10 @@
 use crate::os_input_output::OsApi;
 use crate::panes::{PaneId, PositionAndSize};
 use crate::tab::Pane;
-use std::collections::{BTreeMap, HashSet};
+use std::{
+    cmp::Ordering,
+    collections::{BTreeMap, HashSet},
+};
 
 pub struct PaneResizer<'a> {
     panes: &'a mut BTreeMap<PaneId, Box<dyn Pane>>,
@@ -9,9 +12,7 @@ pub struct PaneResizer<'a> {
 }
 
 // TODO: currently there are some functions here duplicated with Tab
-// the reason for this is that we need to get rid of the expansion_boundary
-// otherwise we'll have a big separation of concerns issue
-// once that is done, all resizing functions should move here
+// all resizing functions should move here
 
 impl<'a> PaneResizer<'a> {
     pub fn new(
@@ -29,63 +30,72 @@ impl<'a> PaneResizer<'a> {
         let mut successfully_resized = false;
         let mut column_difference: isize = 0;
         let mut row_difference: isize = 0;
-        if new_size.columns < current_size.columns {
-            let reduce_by = current_size.columns - new_size.columns;
-            find_reducible_vertical_chain(
-                &self.panes,
-                reduce_by,
-                current_size.columns,
-                current_size.rows,
-            )
-            .map(|panes_to_resize| {
-                self.reduce_panes_left_and_pull_adjacents_left(panes_to_resize, reduce_by);
-                column_difference = new_size.columns as isize - current_size.columns as isize;
-                current_size.columns = (current_size.columns as isize + column_difference) as usize;
-                successfully_resized = true;
-            });
-        } else if new_size.columns > current_size.columns {
-            let increase_by = new_size.columns - current_size.columns;
-            find_increasable_vertical_chain(
-                &self.panes,
-                increase_by,
-                current_size.columns,
-                current_size.rows,
-            )
-            .map(|panes_to_resize| {
-                self.increase_panes_right_and_push_adjacents_right(panes_to_resize, increase_by);
-                column_difference = new_size.columns as isize - current_size.columns as isize;
-                current_size.columns = (current_size.columns as isize + column_difference) as usize;
-                successfully_resized = true;
-            });
+        match new_size.columns.cmp(&current_size.columns) {
+            Ordering::Greater => {
+                let increase_by = new_size.columns - current_size.columns;
+                if let Some(panes_to_resize) = find_increasable_vertical_chain(
+                    &self.panes,
+                    increase_by,
+                    current_size.columns,
+                    current_size.rows,
+                ) {
+                    self.increase_panes_right_and_push_adjacents_right(
+                        panes_to_resize,
+                        increase_by,
+                    );
+                    column_difference = new_size.columns as isize - current_size.columns as isize;
+                    current_size.columns =
+                        (current_size.columns as isize + column_difference) as usize;
+                    successfully_resized = true;
+                };
+            }
+            Ordering::Less => {
+                let reduce_by = current_size.columns - new_size.columns;
+                if let Some(panes_to_resize) = find_reducible_vertical_chain(
+                    &self.panes,
+                    reduce_by,
+                    current_size.columns,
+                    current_size.rows,
+                ) {
+                    self.reduce_panes_left_and_pull_adjacents_left(panes_to_resize, reduce_by);
+                    column_difference = new_size.columns as isize - current_size.columns as isize;
+                    current_size.columns =
+                        (current_size.columns as isize + column_difference) as usize;
+                    successfully_resized = true;
+                };
+            }
+            Ordering::Equal => (),
         }
-        if new_size.rows < current_size.rows {
-            let reduce_by = current_size.rows - new_size.rows;
-            find_reducible_horizontal_chain(
-                &self.panes,
-                reduce_by,
-                current_size.columns,
-                current_size.rows,
-            )
-            .map(|panes_to_resize| {
-                self.reduce_panes_up_and_pull_adjacents_up(panes_to_resize, reduce_by);
-                row_difference = new_size.rows as isize - current_size.rows as isize;
-                current_size.rows = (current_size.rows as isize + row_difference) as usize;
-                successfully_resized = true;
-            });
-        } else if new_size.rows > current_size.rows {
-            let increase_by = new_size.rows - current_size.rows;
-            find_increasable_horizontal_chain(
-                &self.panes,
-                increase_by,
-                current_size.columns,
-                current_size.rows,
-            )
-            .map(|panes_to_resize| {
-                self.increase_panes_down_and_push_down_adjacents(panes_to_resize, increase_by);
-                row_difference = new_size.rows as isize - current_size.rows as isize;
-                current_size.rows = (current_size.rows as isize + row_difference) as usize;
-                successfully_resized = true;
-            });
+        match new_size.rows.cmp(&current_size.rows) {
+            Ordering::Greater => {
+                let increase_by = new_size.rows - current_size.rows;
+                if let Some(panes_to_resize) = find_increasable_horizontal_chain(
+                    &self.panes,
+                    increase_by,
+                    current_size.columns,
+                    current_size.rows,
+                ) {
+                    self.increase_panes_down_and_push_down_adjacents(panes_to_resize, increase_by);
+                    row_difference = new_size.rows as isize - current_size.rows as isize;
+                    current_size.rows = (current_size.rows as isize + row_difference) as usize;
+                    successfully_resized = true;
+                };
+            }
+            Ordering::Less => {
+                let reduce_by = current_size.rows - new_size.rows;
+                if let Some(panes_to_resize) = find_reducible_horizontal_chain(
+                    &self.panes,
+                    reduce_by,
+                    current_size.columns,
+                    current_size.rows,
+                ) {
+                    self.reduce_panes_up_and_pull_adjacents_up(panes_to_resize, reduce_by);
+                    row_difference = new_size.rows as isize - current_size.rows as isize;
+                    current_size.rows = (current_size.rows as isize + row_difference) as usize;
+                    successfully_resized = true;
+                };
+            }
+            Ordering::Equal => (),
         }
         if successfully_resized {
             Some((column_difference, row_difference))
@@ -229,13 +239,12 @@ impl<'a> PaneResizer<'a> {
 
 fn find_next_increasable_horizontal_pane(
     panes: &BTreeMap<PaneId, Box<dyn Pane>>,
-    right_of: &Box<dyn Pane>,
+    right_of: &dyn Pane,
     increase_by: usize,
 ) -> Option<PaneId> {
     let next_pane_candidates = panes.values().filter(
         |p| {
-            p.x() == right_of.x() + right_of.columns() + 1
-                && p.horizontally_overlaps_with(right_of.as_ref())
+            p.x() == right_of.x() + right_of.columns() + 1 && p.horizontally_overlaps_with(right_of)
         }, // TODO: the name here is wrong, it should be vertically_overlaps_with
     );
     let resizable_candidates =
@@ -255,11 +264,11 @@ fn find_next_increasable_horizontal_pane(
 
 fn find_next_increasable_vertical_pane(
     panes: &BTreeMap<PaneId, Box<dyn Pane>>,
-    below: &Box<dyn Pane>,
+    below: &dyn Pane,
     increase_by: usize,
 ) -> Option<PaneId> {
     let next_pane_candidates = panes.values().filter(
-        |p| p.y() == below.y() + below.rows() + 1 && p.vertically_overlaps_with(below.as_ref()), // TODO: the name here is wrong, it should be horizontally_overlaps_with
+        |p| p.y() == below.y() + below.rows() + 1 && p.vertically_overlaps_with(below), // TODO: the name here is wrong, it should be horizontally_overlaps_with
     );
     let resizable_candidates =
         next_pane_candidates.filter(|p| p.can_increase_width_by(increase_by));
@@ -278,11 +287,11 @@ fn find_next_increasable_vertical_pane(
 
 fn find_next_reducible_vertical_pane(
     panes: &BTreeMap<PaneId, Box<dyn Pane>>,
-    below: &Box<dyn Pane>,
+    below: &dyn Pane,
     reduce_by: usize,
 ) -> Option<PaneId> {
     let next_pane_candidates = panes.values().filter(
-        |p| p.y() == below.y() + below.rows() + 1 && p.vertically_overlaps_with(below.as_ref()), // TODO: the name here is wrong, it should be horizontally_overlaps_with
+        |p| p.y() == below.y() + below.rows() + 1 && p.vertically_overlaps_with(below), // TODO: the name here is wrong, it should be horizontally_overlaps_with
     );
     let resizable_candidates = next_pane_candidates.filter(|p| p.can_reduce_width_by(reduce_by));
     resizable_candidates.fold(None, |next_pane_id, p| match next_pane_id {
@@ -300,13 +309,12 @@ fn find_next_reducible_vertical_pane(
 
 fn find_next_reducible_horizontal_pane(
     panes: &BTreeMap<PaneId, Box<dyn Pane>>,
-    right_of: &Box<dyn Pane>,
+    right_of: &dyn Pane,
     reduce_by: usize,
 ) -> Option<PaneId> {
     let next_pane_candidates = panes.values().filter(
         |p| {
-            p.x() == right_of.x() + right_of.columns() + 1
-                && p.horizontally_overlaps_with(right_of.as_ref())
+            p.x() == right_of.x() + right_of.columns() + 1 && p.horizontally_overlaps_with(right_of)
         }, // TODO: the name here is wrong, it should be vertically_overlaps_with
     );
     let resizable_candidates = next_pane_candidates.filter(|p| p.can_reduce_height_by(reduce_by));
@@ -351,7 +359,11 @@ fn find_increasable_horizontal_chain(
                     if current_pane.x() + current_pane.columns() == screen_width {
                         return Some(panes_to_resize);
                     }
-                    match find_next_increasable_horizontal_pane(panes, &current_pane, increase_by) {
+                    match find_next_increasable_horizontal_pane(
+                        panes,
+                        current_pane.as_ref(),
+                        increase_by,
+                    ) {
                         Some(next_pane_id) => {
                             current_pane = panes.get(&next_pane_id).unwrap();
                         }
@@ -397,7 +409,11 @@ fn find_increasable_vertical_chain(
                     if current_pane.y() + current_pane.rows() == screen_height {
                         return Some(panes_to_resize);
                     }
-                    match find_next_increasable_vertical_pane(panes, &current_pane, increase_by) {
+                    match find_next_increasable_vertical_pane(
+                        panes,
+                        current_pane.as_ref(),
+                        increase_by,
+                    ) {
                         Some(next_pane_id) => {
                             current_pane = panes.get(&next_pane_id).unwrap();
                         }
@@ -443,7 +459,11 @@ fn find_reducible_horizontal_chain(
                     if current_pane.x() + current_pane.columns() == screen_width {
                         return Some(panes_to_resize);
                     }
-                    match find_next_reducible_horizontal_pane(panes, &current_pane, reduce_by) {
+                    match find_next_reducible_horizontal_pane(
+                        panes,
+                        current_pane.as_ref(),
+                        reduce_by,
+                    ) {
                         Some(next_pane_id) => {
                             current_pane = panes.get(&next_pane_id).unwrap();
                         }
@@ -489,7 +509,11 @@ fn find_reducible_vertical_chain(
                     if current_pane.y() + current_pane.rows() == screen_height {
                         return Some(panes_to_resize);
                     }
-                    match find_next_reducible_vertical_pane(panes, &current_pane, increase_by) {
+                    match find_next_reducible_vertical_pane(
+                        panes,
+                        current_pane.as_ref(),
+                        increase_by,
+                    ) {
                         Some(next_pane_id) => {
                             current_pane = panes.get(&next_pane_id).unwrap();
                         }
diff --git a/src/client/panes/grid.rs b/src/client/panes/grid.rs
index 7651bdc0..c6dd201e 100644
--- a/src/client/panes/grid.rs
+++ b/src/client/panes/grid.rs
@@ -1,9 +1,13 @@
 use std::{
     cmp::Ordering,
+    collections::VecDeque,
     fmt::{self, Debug, Formatter},
 };
 
-static TABSTOP_WIDTH: usize = 8; // TODO: is this always right?
+const TABSTOP_WIDTH: usize = 8; // TODO: is this always right?
+const SCROLL_BACK: usize = 10_000;
+
+use crate::utils::logging::debug_log_to_file;
 
 use crate::panes::terminal_character::{
     CharacterStyles, TerminalCharacter, EMPTY_TERMINAL_CHARACTER,
@@ -26,14 +30,12 @@ fn get_top_non_canonical_rows(rows: &mut Vec<Row>) -> Vec<Row> {
     }
 }
 
-fn get_bottom_canonical_row_and_wraps(rows: &mut Vec<Row>) -> Vec<Row> {
+fn get_bottom_canonical_row_and_wraps(rows: &mut VecDeque<Row>) -> Vec<Row> {
     let mut index_of_last_non_canonical_row = None;
     for (i, row) in rows.iter().enumerate().rev() {
+        index_of_last_non_canonical_row = Some(i);
         if row.is_canonical {
-            index_of_last_non_canonical_row = Some(i);
             break;
-        } else {
-            index_of_last_non_canonical_row = Some(i);
         }
     }
     match index_of_last_non_canonical_row {
@@ -45,7 +47,7 @@ fn get_bottom_canonical_row_and_wraps(rows: &mut Vec<Row>) -> Vec<Row> {
 }
 
 fn transfer_rows_down(
-    source: &mut Vec<Row>,
+    source: &mut VecDeque<Row>,
     destination: &mut Vec<Row>,
     count: usize,
     max_src_width: Option<usize>,
@@ -58,7 +60,7 @@ fn transfer_rows_down(
             break;
         }
         if next_lines.is_empty() {
-            match source.pop() {
+            match source.pop_back() {
                 Some(next_line) => {
                     let mut top_non_canonical_rows_in_dst = get_top_non_canonical_rows(destination);
                     lines_added_to_destination -= top_non_canonical_rows_in_dst.len() as isize;
@@ -84,13 +86,12 @@ fn transfer_rows_down(
     if !next_lines.is_empty() {
         match max_src_width {
             Some(max_row_width) => {
-                let mut excess_rows =
-                    Row::from_rows(next_lines).split_to_rows_of_length(max_row_width);
-                source.append(&mut excess_rows);
+                let excess_rows = Row::from_rows(next_lines).split_to_rows_of_length(max_row_width);
+                source.extend(excess_rows);
             }
             None => {
                 let excess_row = Row::from_rows(next_lines);
-                source.push(excess_row);
+                bounded_push(source, excess_row);
             }
         }
     }
@@ -98,7 +99,7 @@ fn transfer_rows_down(
 
 fn transfer_rows_up(
     source: &mut Vec<Row>,
-    destination: &mut Vec<Row>,
+    destination: &mut VecDeque<Row>,
     count: usize,
     max_src_width: Option<usize>,
     max_dst_width: Option<usize>,
@@ -124,7 +125,7 @@ fn transfer_rows_up(
                 break; // no more rows
             }
         }
-        destination.push(next_lines.remove(0));
+        bounded_push(destination, next_lines.remove(0));
     }
     if !next_lines.is_empty() {
         match max_src_width {
@@ -142,13 +143,25 @@ fn transfer_rows_up(
     }
 }
 
+fn bounded_push(vec: &mut VecDeque<Row>, value: Row) {
+    if vec.len() >= SCROLL_BACK {
+        vec.pop_front();
+    }
+    vec.push_back(value)
+}
+
 #[derive(Clone)]
 pub struct Grid {
-    lines_above: Vec<Row>,
+    lines_above: VecDeque<Row>,
     viewport: Vec<Row>,
     lines_below: Vec<Row>,
+    alternative_lines_above_viewport_and_cursor: Option<(VecDeque<Row>, Vec<Row>, Cursor)>,
     cursor: Cursor,
     scroll_region: Option<(usize, usize)>,
+    pending_styles: CharacterStyles,
+    pub should_render: bool,
+    pub cursor_key_mode: bool, // DECCKM - when set, cursor keys should send ANSI direction codes (eg. "OD") instead of the arrow keys (eg. "")
+    pub clear_viewport_before_rendering: bool,
     pub width: usize,
     pub height: usize,
 }
@@ -169,13 +182,18 @@ impl Debug for Grid {
 impl Grid {
     pub fn new(rows: usize, columns: usize) -> Self {
         Grid {
-            lines_above: vec![],
+            lines_above: VecDeque::with_capacity(SCROLL_BACK),
             viewport: vec![Row::new().canonical()],
             lines_below: vec![],
             cursor: Cursor::new(0, 0),
             scroll_region: None,
             width: columns,
             height: rows,
+            pending_styles: CharacterStyles::new(),
+            should_render: true,
+            cursor_key_mode: false,
+            alternative_lines_above_viewport_and_cursor: None,
+            clear_viewport_before_rendering: false,
         }
     }
     pub fn advance_to_next_tabstop(&mut self, styles: CharacterStyles) {
@@ -237,7 +255,7 @@ impl Grid {
         if !self.lines_above.is_empty() && self.viewport.len() == self.height {
             let line_to_push_down = self.viewport.pop().unwrap();
             self.lines_below.insert(0, line_to_push_down);
-            let line_to_insert_at_viewport_top = self.lines_above.pop().unwrap();
+            let line_to_insert_at_viewport_top = self.lines_above.pop_back().unwrap();
             self.viewport.insert(0, line_to_insert_at_viewport_top);
         }
     }
@@ -245,11 +263,11 @@ impl Grid {
         if !self.lines_below.is_empty() && self.viewport.len() == self.height {
             let mut line_to_push_up = self.viewport.remove(0);
             if line_to_push_up.is_canonical {
-                self.lines_above.push(line_to_push_up);
+                bounded_push(&mut self.lines_above, line_to_push_up);
             } else {
-                let mut last_line_above = self.lines_above.pop().unwrap();
+                let mut last_line_above = self.lines_above.pop_back().unwrap();
                 last_line_above.append(&mut line_to_push_up.columns);
-                self.lines_above.push(last_line_above);
+                bounded_push(&mut self.lines_above, last_line_above);
             }
             let line_to_insert_at_viewport_bottom = self.lines_below.remove(0);
             self.viewport.push(line_to_insert_at_viewport_bottom);
@@ -265,7 +283,7 @@ impl Grid {
                     && viewport_canonical_lines.is_empty()
                     && !self.lines_above.is_empty()
                 {
-                    let mut first_line_above = self.lines_above.pop().unwrap();
+                    let mut first_line_above = self.lines_above.pop_back().unwrap();
                     first_line_above.append(&mut row.columns);
                     viewport_canonical_lines.push(first_line_above);
                     cursor_canonical_line_index += 1;
@@ -429,13 +447,35 @@ impl Grid {
             self.scroll_down_one_line();
         }
     }
-    pub fn rotate_scroll_region_up(&mut self, _count: usize) {
-        // TBD
+    pub fn rotate_scroll_region_up(&mut self, count: usize) {
+        if let Some((scroll_region_top, scroll_region_bottom)) = self.scroll_region {
+            for _ in 0..count {
+                let columns = vec![EMPTY_TERMINAL_CHARACTER; self.width];
+                if scroll_region_bottom < self.viewport.len() {
+                    self.viewport.remove(scroll_region_bottom);
+                }
+                if scroll_region_top < self.viewport.len() {
+                    self.viewport
+                        .insert(scroll_region_top, Row::from_columns(columns).canonical());
+                }
+            }
+        }
     }
-    pub fn rotate_scroll_region_down(&mut self, _count: usize) {
-        // TBD
+    pub fn rotate_scroll_region_down(&mut self, count: usize) {
+        if let Some((scroll_region_top, scroll_region_bottom)) = self.scroll_region {
+            for _ in 0..count {
+                let columns = vec![EMPTY_TERMINAL_CHARACTER; self.width];
+                self.viewport.remove(scroll_region_top);
+                if self.viewport.len() > scroll_region_top {
+                    self.viewport
+                        .insert(scroll_region_bottom, Row::from_columns(columns).canonical());
+                } else {
+                    self.viewport.push(Row::from_columns(columns).canonical());
+                }
+            }
+        }
     }
-    pub fn add_canonical_line(&mut self, pad_character: TerminalCharacter) {
+    pub fn add_canonical_line(&mut self) {
         if let Some((scroll_region_top, scroll_region_bottom)) = self.scroll_region {
             if self.cursor.y == scroll_region_bottom {
                 // end of scroll region
@@ -444,8 +484,12 @@ impl Grid {
                 // then we add an empty line at its end which will be filled by the application
                 // controlling the scroll region (presumably filled by whatever comes next in the
                 // scroll buffer, but that's not something we control)
+                if scroll_region_top >= self.viewport.len() {
+                    // the state is corrupted
+                    return;
+                }
                 self.viewport.remove(scroll_region_top);
-                let columns = vec![pad_character; self.width];
+                let columns = vec![EMPTY_TERMINAL_CHARACTER; self.width];
                 self.viewport
                     .insert(scroll_region_bottom, Row::from_columns(columns).canonical());
                 return;
@@ -483,6 +527,24 @@ impl Grid {
     }
     pub fn insert_character_at_cursor_position(&mut self, terminal_character: TerminalCharacter) {
         match self.viewport.get_mut(self.cursor.y) {
+            Some(row) => {
+                row.insert_character_at(terminal_character, self.cursor.x);
+                if row.len() > self.width {
+                    row.truncate(self.width);
+                }
+            }
+            None => {
+                // pad lines until cursor if they do not exist
+                for _ in self.viewport.len()..self.cursor.y {
+                    self.viewport.push(Row::new().canonical());
+                }
+                self.viewport
+                    .push(Row::new().with_character(terminal_character).canonical());
+            }
+        }
+    }
+    pub fn add_character_at_cursor_position(&mut self, terminal_character: TerminalCharacter) {
+        match self.viewport.get_mut(self.cursor.y) {
             Some(row) => row.add_character_at(terminal_character, self.cursor.x),
             None => {
                 // pad lines until cursor if they do not exist
@@ -496,9 +558,7 @@ impl Grid {
     }
     pub fn add_character(&mut self, terminal_character: TerminalCharacter) {
         // TODO: try to separate adding characters from moving the cursors in this function
-        if self.cursor.x < self.width {
-            self.insert_character_at_cursor_position(terminal_character);
-        } else {
+        if self.cursor.x >= self.width {
             // line wrap
             self.cursor.x = 0;
             if self.cursor.y == self.height - 1 {
@@ -519,8 +579,8 @@ impl Grid {
                     self.viewport.push(line_wrapped_row);
                 }
             }
-            self.insert_character_at_cursor_position(terminal_character);
         }
+        self.add_character_at_cursor_position(terminal_character);
         self.move_cursor_forward_until_edge(1);
     }
     pub fn move_cursor_forward_until_edge(&mut self, count: usize) {
@@ -546,15 +606,17 @@ impl Grid {
         row.replace_beginning_with(line_part);
     }
     pub fn clear_all_after_cursor(&mut self, replace_with: TerminalCharacter) {
-        let cursor_row = self.viewport.get_mut(self.cursor.y).unwrap();
-        cursor_row.truncate(self.cursor.x);
-        let mut replace_with_columns_in_cursor_row = vec![replace_with; self.width - self.cursor.x];
-        cursor_row.append(&mut replace_with_columns_in_cursor_row);
+        if let Some(cursor_row) = self.viewport.get_mut(self.cursor.y).as_mut() {
+            cursor_row.truncate(self.cursor.x);
+            let mut replace_with_columns_in_cursor_row =
+                vec![replace_with; self.width - self.cursor.x];
+            cursor_row.append(&mut replace_with_columns_in_cursor_row);
 
-        let replace_with_columns = vec![replace_with; self.width];
-        self.replace_characters_in_line_after_cursor(replace_with);
-        for row in self.viewport.iter_mut().skip(self.cursor.y + 1) {
-            row.replace_columns(replace_with_columns.clone());
+            let replace_with_columns = vec![replace_with; self.width];
+            self.replace_characters_in_line_after_cursor(replace_with);
+            for row in self.viewport.iter_mut().skip(self.cursor.y + 1) {
+                row.replace_columns(replace_with_columns.clone());
+            }
         }
     }
     pub fn clear_cursor_line(&mut self) {
@@ -600,7 +662,9 @@ impl Grid {
             if current_line_index == scroll_region_top {
                 // if we're at the top line, we create a new line and remove the last line that
                 // would otherwise overflow
-                self.viewport.remove(scroll_region_bottom);
+                if scroll_region_bottom < self.viewport.len() {
+                    self.viewport.remove(scroll_region_bottom);
+                }
                 self.viewport.insert(current_line_index, Row::new()); // TODO: .canonical() ?
             } else if current_line_index > scroll_region_top
                 && current_line_index <= scroll_region_bottom
@@ -621,7 +685,7 @@ impl Grid {
             self.cursor.y + count
         };
         for _ in 0..lines_to_add {
-            self.add_canonical_line(pad_character);
+            self.add_canonical_line();
         }
         self.pad_lines_until(self.cursor.y, pad_character);
     }
@@ -663,8 +727,12 @@ impl Grid {
                 for _ in 0..count {
                     self.viewport.remove(current_line_index);
                     let columns = vec![pad_character; self.width];
-                    self.viewport
-                        .insert(scroll_region_bottom, Row::from_columns(columns).canonical());
+                    if self.viewport.len() > scroll_region_bottom {
+                        self.viewport
+                            .insert(scroll_region_bottom, Row::from_columns(columns).canonical());
+                    } else {
+                        self.viewport.push(Row::from_columns(columns).canonical());
+                    }
                 }
             }
         }
@@ -683,7 +751,9 @@ impl Grid {
                 // so we add an empty line where the cursor currently is, and delete the last line
                 // of the scroll region
                 for _ in 0..count {
-                    self.viewport.remove(scroll_region_bottom);
+                    if scroll_region_bottom < self.viewport.len() {
+                        self.viewport.remove(scroll_region_bottom);
+                    }
                     let columns = vec![pad_character; self.width];
                     self.viewport
                         .insert(current_line_index, Row::from_columns(columns).canonical());
@@ -723,6 +793,320 @@ impl Grid {
             .unwrap()
             .append(&mut empty_space_to_append);
     }
+    fn add_newline(&mut self) {
+        self.add_canonical_line();
+        self.mark_for_rerender();
+    }
+    pub fn mark_for_rerender(&mut self) {
+        self.should_render = true;
+    }
+    fn reset_terminal_state(&mut self) {
+        self.lines_above = VecDeque::with_capacity(SCROLL_BACK);
+        self.lines_below = vec![];
+        self.viewport = vec![Row::new().canonical()];
+        self.alternative_lines_above_viewport_and_cursor = None;
+        self.cursor_key_mode = false;
+        self.scroll_region = None;
+        self.clear_viewport_before_rendering = true;
+        self.cursor = Cursor::new(0, 0);
+    }
+}
+
+impl vte::Perform for Grid {
+    fn print(&mut self, c: char) {
+        // apparently, building TerminalCharacter like this without a "new" method
+        // is a little faster
+        let terminal_character = TerminalCharacter {
+            character: c,
+            styles: self.pending_styles,
+        };
+        self.add_character(terminal_character);
+    }
+
+    fn execute(&mut self, byte: u8) {
+        match byte {
+            8 => {
+                // backspace
+                self.move_cursor_backwards(1);
+            }
+            9 => {
+                // tab
+                self.advance_to_next_tabstop(self.pending_styles);
+            }
+            10 => {
+                // 0a, newline
+                self.add_newline();
+            }
+            13 => {
+                // 0d, carriage return
+                self.move_cursor_to_beginning_of_line();
+            }
+            _ => {}
+        }
+    }
+
+    fn hook(&mut self, _params: &[i64], _intermediates: &[u8], _ignore: bool, _c: char) {
+        // TBD
+    }
+
+    fn put(&mut self, _byte: u8) {
+        // TBD
+    }
+
+    fn unhook(&mut self) {
+        // TBD
+    }
+
+    fn osc_dispatch(&mut self, _params: &[&[u8]], _bell_terminated: bool) {
+        // TBD
+    }
+
+    fn csi_dispatch(&mut self, params: &[i64], _intermediates: &[u8], _ignore: bool, c: char) {
+        if c == 'm' {
+            self.pending_styles.add_style_from_ansi_params(params);
+        } else if c == 'C' {
+            // move cursor forward
+            let move_by = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            self.move_cursor_forward_until_edge(move_by);
+        } else if c == 'K' {
+            // clear line (0 => right, 1 => left, 2 => all)
+            if params[0] == 0 {
+                let mut char_to_replace = EMPTY_TERMINAL_CHARACTER;
+                char_to_replace.styles = self.pending_styles;
+                self.replace_characters_in_line_after_cursor(char_to_replace);
+            } else if params[0] == 1 {
+                let mut char_to_replace = EMPTY_TERMINAL_CHARACTER;
+                char_to_replace.styles = self.pending_styles;
+                self.replace_characters_in_line_before_cursor(char_to_replace);
+            } else if params[0] == 2 {
+                self.clear_cursor_line();
+            }
+        } else if c == 'J' {
+            // clear all (0 => below, 1 => above, 2 => all, 3 => saved)
+            let mut char_to_replace = EMPTY_TERMINAL_CHARACTER;
+            char_to_replace.styles = self.pending_styles;
+            if params[0] == 0 {
+                self.clear_all_after_cursor(char_to_replace);
+            } else if params[0] == 2 {
+                self.clear_all(char_to_replace);
+            }
+        // TODO: implement 1
+        } else if c == 'H' {
+            // goto row/col
+            // we subtract 1 from the row/column because these are 1 indexed
+            // (except when they are 0, in which case they should be 1
+            // don't look at me, I don't make the rules)
+            let (row, col) = if params.len() == 1 {
+                if params[0] == 0 {
+                    (0, params[0] as usize)
+                } else {
+                    ((params[0] as usize).saturating_sub(1), params[0] as usize)
+                }
+            } else if params[0] == 0 {
+                (0, (params[1] as usize).saturating_sub(1))
+            } else {
+                (
+                    (params[0] as usize).saturating_sub(1),
+                    (params[1] as usize).saturating_sub(1),
+                )
+            };
+            let pad_character = EMPTY_TERMINAL_CHARACTER;
+            self.move_cursor_to(col, row, pad_character);
+        } else if c == 'A' {
+            // move cursor up until edge of screen
+            let move_up_count = if params[0] == 0 { 1 } else { params[0] };
+            self.move_cursor_up(move_up_count as usize);
+        } else if c == 'B' {
+            // move cursor down until edge of screen
+            let move_down_count = if params[0] == 0 { 1 } else { params[0] };
+            let pad_character = EMPTY_TERMINAL_CHARACTER;
+            self.move_cursor_down(move_down_count as usize, pad_character);
+        } else if c == 'D' {
+            let move_back_count = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            self.move_cursor_back(move_back_count);
+        } else if c == 'l' {
+            let first_intermediate_is_questionmark = match _intermediates.get(0) {
+                Some(b'?') => true,
+                None => false,
+                _ => false,
+            };
+            if first_intermediate_is_questionmark {
+                match params.get(0) {
+                    Some(&1049) => {
+                        if let Some((
+                            alternative_lines_above,
+                            alternative_viewport,
+                            alternative_cursor,
+                        )) = self.alternative_lines_above_viewport_and_cursor.as_mut()
+                        {
+                            std::mem::swap(&mut self.lines_above, alternative_lines_above);
+                            std::mem::swap(&mut self.viewport, alternative_viewport);
+                            std::mem::swap(&mut self.cursor, alternative_cursor);
+                        }
+                        self.alternative_lines_above_viewport_and_cursor = None;
+                        self.clear_viewport_before_rendering = true;
+                        self.change_size(self.height, self.width); // the alternative_viewport might have been of a different size...
+                        self.mark_for_rerender();
+                    }
+                    Some(&25) => {
+                        self.hide_cursor();
+                        self.mark_for_rerender();
+                    }
+                    Some(&1) => {
+                        self.cursor_key_mode = false;
+                    }
+                    _ => {}
+                };
+            }
+        } else if c == 'h' {
+            let first_intermediate_is_questionmark = match _intermediates.get(0) {
+                Some(b'?') => true,
+                None => false,
+                _ => false,
+            };
+            if first_intermediate_is_questionmark {
+                match params.get(0) {
+                    Some(&25) => {
+                        self.show_cursor();
+                        self.mark_for_rerender();
+                    }
+                    Some(&1049) => {
+                        let current_lines_above = std::mem::replace(
+                            &mut self.lines_above,
+                            VecDeque::with_capacity(SCROLL_BACK),
+                        );
+                        let current_viewport =
+                            std::mem::replace(&mut self.viewport, vec![Row::new().canonical()]);
+                        let current_cursor = std::mem::replace(&mut self.cursor, Cursor::new(0, 0));
+                        self.alternative_lines_above_viewport_and_cursor =
+                            Some((current_lines_above, current_viewport, current_cursor));
+                        self.clear_viewport_before_rendering = true;
+                    }
+                    Some(&1) => {
+                        self.cursor_key_mode = true;
+                    }
+                    _ => {}
+                };
+            }
+        } else if c == 'r' {
+            if params.len() > 1 {
+                // minus 1 because these are 1 indexed
+                let top_line_index = (params[0] as usize).saturating_sub(1);
+                let bottom_line_index = (params[1] as usize).saturating_sub(1);
+                self.set_scroll_region(top_line_index, bottom_line_index);
+                self.show_cursor();
+            } else {
+                self.clear_scroll_region();
+            }
+        } else if c == 'M' {
+            // delete lines if currently inside scroll region
+            let line_count_to_delete = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            let pad_character = EMPTY_TERMINAL_CHARACTER;
+            self.delete_lines_in_scroll_region(line_count_to_delete, pad_character);
+        } else if c == 'L' {
+            // insert blank lines if inside scroll region
+            let line_count_to_add = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            let pad_character = EMPTY_TERMINAL_CHARACTER;
+            self.add_empty_lines_in_scroll_region(line_count_to_add, pad_character);
+        } else if c == 'q' {
+            // ignore for now to run on mac
+        } else if c == 'G' {
+            let column = if params[0] == 0 {
+                0
+            } else {
+                params[0] as usize - 1
+            };
+            self.move_cursor_to_column(column);
+        } else if c == 'd' {
+            // goto line
+            let line = if params[0] == 0 {
+                1
+            } else {
+                // minus 1 because this is 1 indexed
+                params[0] as usize - 1
+            };
+            let pad_character = EMPTY_TERMINAL_CHARACTER;
+            self.move_cursor_to_line(line, pad_character);
+        } else if c == 'P' {
+            // erase characters
+            let count = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            self.erase_characters(count, self.pending_styles);
+        } else if c == 'X' {
+            // erase characters and replace with empty characters of current style
+            let count = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            self.replace_with_empty_chars(count, self.pending_styles);
+        } else if c == 'T' {
+            /*
+             * 124  54  T   SD
+             * Scroll down, new lines inserted at top of screen
+             * [4T = Scroll down 4, bring previous lines back into view
+             */
+            let line_count: i64 = *params.get(0).expect("A number of lines was expected.");
+
+            if line_count >= 0 {
+                self.rotate_scroll_region_up(line_count as usize);
+            } else {
+                // TODO: can this actually happen?
+                self.rotate_scroll_region_down(line_count.abs() as usize);
+            }
+        } else if c == 'S' {
+            // move scroll up
+            let count = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            self.rotate_scroll_region_down(count);
+        } else if c == '@' {
+            let count = if params[0] == 0 {
+                1
+            } else {
+                params[0] as usize
+            };
+            for _ in 0..count {
+                // TODO: should this be styled?
+                self.insert_character_at_cursor_position(EMPTY_TERMINAL_CHARACTER);
+            }
+        } else {
+            let _ = debug_log_to_file(format!("Unhandled csi: {}->{:?}", c, params));
+        }
+    }
+
+    fn esc_dispatch(&mut self, intermediates: &[u8], _ignore: bool, byte: u8) {
+        match (byte, intermediates.get(0)) {
+            (b'M', None) => {
+                self.move_cursor_up_with_scrolling(1);
+            }
+            (b'c', None) => {
+                self.reset_terminal_state();
+            }
+            _ => {}
+        }
+    }
 }
 
 #[derive(Clone)]
@@ -786,10 +1170,24 @@ impl Row {
             }
         }
     }
+    pub fn insert_character_at(&mut self, terminal_character: TerminalCharacter, x: usize) {
+        match self.columns.len().cmp(&x) {
+            Ordering::Equal => self.columns.push(terminal_character),
+            Ordering::Less => {
+                self.columns.resize(x, EMPTY_TERMINAL_CHARACTER);
+                self.columns.push(terminal_character);
+            }
+            Ordering::Greater => {
+                self.columns.insert(x, terminal_character);
+            }
+        }
+    }
     pub fn replace_character_at(&mut self, terminal_character: TerminalCharacter, x: usize) {
         // this is much more performant than remove/insert
-        self.columns.push(terminal_character);
-        self.columns.swap_remove(x);
+        if x < self.columns.len() {
+            self.columns.push(terminal_character);
+            self.columns.swap_remove(x);
+        }
     }
     pub fn replace_columns(&mut self, columns: Vec<TerminalCharacter>) {
         self.columns = columns;
@@ -804,7 +1202,11 @@ impl Row {
         self.columns.append(to_append);
     }
     pub fn replace_beginning_with(&mut self, mut line_part: Vec<TerminalCharacter>) {
-        drop(self.columns.drain(0..line_part.len()));
+        if line_part.len() > self.columns.len() {
+            self.columns.clear();
+        } else {
+            drop(self.columns.drain(0..line_part.len()));
+        }
         line_part.append(&mut self.columns);
         self.columns = line_part;
     }
@@ -812,7 +1214,9 @@ impl Row {
         self.columns.len()
     }
     pub fn delete_character(&mut self, x: usize) {
-        self.columns.remove(x);
+        if x < self.columns.len() {
+            self.columns.remove(x);
+        }
     }
     pub fn split_to_rows_of_length(&mut self, max_row_length: usize) -> Vec<Row> {
         let mut parts: Vec<Row> = vec![];
diff --git a/src/client/panes/plugin_pane.rs b/src/client/panes/plugin_pane.rs
index 49cf2aee..24daec08 100644
--- a/src/client/panes/plugin_pane.rs
+++ b/src/client/panes/plugin_pane.rs
@@ -1,5 +1,3 @@
-#![allow(clippy::clippy::if_same_then_else)]
-
 use crate::{common::SenderWithContext, pty_bus::VteBytes, tab::Pane, wasm_vm::PluginInstruction};
 
 use std::{sync::mpsc::channel, unimplemented};
diff --git a/src/client/panes/terminal_character.rs b/src/client/panes/terminal_character.rs
index ce967ef8..7569e993 100644
--- a/src/client/panes/terminal_character.rs
+++ b/src/client/panes/terminal_character.rs
@@ -48,7 +48,7 @@ pub enum NamedColor {
 }
 
 impl NamedColor {
-    fn to_foreground_ansi_code(&self) -> String {
+    fn to_foreground_ansi_code(self) -> String {
         match self {
             NamedColor::Black => format!("{}", 30),
             NamedColor::Red => format!("{}", 31),
@@ -68,7 +68,7 @@ impl NamedColor {
             NamedColor::BrightWhite => format!("{}", 97),
         }
     }
-    fn to_background_ansi_code(&self) -> String {
+    fn to_background_ansi_code(self) -> String {
         match self {
             NamedColor::Black => format!("{}", 40),
             NamedColor::Red => format!("{}", 41),
diff --git a/src/client/panes/terminal_pane.rs b/src/client/panes/terminal_pane.rs
index d2473ba3..5d63a100 100644
--- a/src/client/panes/terminal_pane.rs
+++ b/src/client/panes/terminal_pane.rs
@@ -1,5 +1,3 @@
-#![allow(clippy::clippy::if_same_then_else)]
-
 use crate::tab::Pane;
 use ::nix::pty::Winsize;
 use ::std::os::unix::io::RawFd;
@@ -10,7 +8,6 @@ use crate::panes::terminal_character::{
     CharacterStyles, TerminalCharacter, EMPTY_TERMINAL_CHARACTER,
 };
 use crate::pty_bus::VteBytes;
-use crate::utils::logging::debug_log_to_file;
 
 #[derive(PartialEq, Eq, Ord, PartialOrd, Hash, Clone, Copy, Debug)]
 pub enum PaneId {
@@ -38,19 +35,14 @@ impl From<Winsize> for PositionAndSize {
     }
 }
 
-#[derive(Debug)]
 pub struct TerminalPane {
     pub grid: Grid,
-    pub alternative_grid: Option<Grid>, // for 1049h/l instructions which tell us to switch between these two
     pub pid: RawFd,
-    pub should_render: bool,
     pub selectable: bool,
     pub position_and_size: PositionAndSize,
     pub position_and_size_override: Option<PositionAndSize>,
-    pub cursor_key_mode: bool, // DECCKM - when set, cursor keys should send ANSI direction codes (eg. "OD") instead of the arrow keys (eg. "")
     pub max_height: Option<usize>,
-    pending_styles: CharacterStyles,
-    clear_viewport_before_rendering: bool,
+    vte_parser: vte::Parser,
 }
 
 impl Pane for TerminalPane {
@@ -86,9 +78,8 @@ impl Pane for TerminalPane {
         self.reflow_lines();
     }
     fn handle_pty_bytes(&mut self, bytes: VteBytes) {
-        let mut vte_parser = vte::Parser::new();
         for byte in bytes.iter() {
-            vte_parser.advance(self, *byte);
+            self.vte_parser.advance(&mut self.grid, *byte);
         }
     }
     fn cursor_coordinates(&self) -> Option<(usize, usize)> {
@@ -103,7 +94,7 @@ impl Pane for TerminalPane {
         match input_bytes.as_slice() {
             [27, 91, 68] => {
                 // left arrow
-                if self.cursor_key_mode {
+                if self.grid.cursor_key_mode {
                     // please note that in the line below, there is an ANSI escape code (27) at the beginning of the string,
                     // some editors will not show this
                     return "OD".as_bytes().to_vec();
@@ -111,7 +102,7 @@ impl Pane for TerminalPane {
             }
             [27, 91, 67] => {
                 // right arrow
-                if self.cursor_key_mode {
+                if self.grid.cursor_key_mode {
                     // please note that in the line below, there is an ANSI escape code (27) at the beginning of the string,
                     // some editors will not show this
                     return "OC".as_bytes().to_vec();
@@ -119,7 +110,7 @@ impl Pane for TerminalPane {
             }
             [27, 91, 65] => {
                 // up arrow
-                if self.cursor_key_mode {
+                if self.grid.cursor_key_mode {
                     // please note that in the line below, there is an ANSI escape code (27) at the beginning of the string,
                     // some editors will not show this
                     return "OA".as_bytes().to_vec();
@@ -127,7 +118,7 @@ impl Pane for TerminalPane {
             }
             [27, 91, 66] => {
                 // down arrow
-                if self.cursor_key_mode {
+                if self.grid.cursor_key_mode {
                     // please note that in the line below, there is an ANSI escape code (27) at the beginning of the string,
                     // some editors will not show this
                     return "OB".as_bytes().to_vec();
@@ -142,10 +133,10 @@ impl Pane for TerminalPane {
         self.position_and_size_override
     }
     fn should_render(&self) -> bool {
-        self.should_render
+        self.grid.should_render
     }
     fn set_should_render(&mut self, should_render: bool) {
-        self.should_render = should_render;
+        self.grid.should_render = should_render;
     }
     fn selectable(&self) -> bool {
         self.selectable
@@ -175,7 +166,7 @@ impl Pane for TerminalPane {
             let buffer_lines = &self.read_buffer_as_lines();
             let display_cols = self.get_columns();
             let mut character_styles = CharacterStyles::new();
-            if self.clear_viewport_before_rendering {
+            if self.grid.clear_viewport_before_rendering {
                 for line_index in 0..self.grid.height {
                     let x = self.get_x();
                     let y = self.get_y();
@@ -188,7 +179,7 @@ impl Pane for TerminalPane {
                         vte_output.push(EMPTY_TERMINAL_CHARACTER.character);
                     }
                 }
-                self.clear_viewport_before_rendering = false;
+                self.grid.clear_viewport_before_rendering = false;
             }
             for (row, line) in buffer_lines.iter().enumerate() {
                 let x = self.get_x();
@@ -212,7 +203,7 @@ impl Pane for TerminalPane {
                 }
                 character_styles.clear();
             }
-            self.should_render = false;
+            self.grid.should_render = false;
             Some(vte_output)
         } else {
             None
@@ -271,40 +262,31 @@ impl Pane for TerminalPane {
     }
     fn scroll_up(&mut self, count: usize) {
         self.grid.move_viewport_up(count);
-        self.mark_for_rerender();
+        self.grid.should_render = true;
     }
     fn scroll_down(&mut self, count: usize) {
         self.grid.move_viewport_down(count);
-        self.mark_for_rerender();
+        self.grid.should_render = true;
     }
     fn clear_scroll(&mut self) {
         self.grid.reset_viewport();
-        self.mark_for_rerender();
+        self.grid.should_render = true;
     }
 }
 
 impl TerminalPane {
     pub fn new(pid: RawFd, position_and_size: PositionAndSize) -> TerminalPane {
         let grid = Grid::new(position_and_size.rows, position_and_size.columns);
-        let pending_styles = CharacterStyles::new();
-
         TerminalPane {
             pid,
             grid,
-            alternative_grid: None,
-            should_render: true,
             selectable: true,
-            pending_styles,
             position_and_size,
             position_and_size_override: None,
-            cursor_key_mode: false,
-            clear_viewport_before_rendering: false,
             max_height: None,
+            vte_parser: vte::Parser::new(),
         }
     }
-    pub fn mark_for_rerender(&mut self) {
-        self.should_render = true;
-    }
     pub fn get_x(&self) -> usize {
         match self.position_and_size_override {
             Some(position_and_size_override) => position_and_size_override.x,
@@ -333,11 +315,7 @@ impl TerminalPane {
         let rows = self.get_rows();
         let columns = self.get_columns();
         self.grid.change_size(rows, columns);
-        if let Some(alternative_grid) = self.alternative_grid.as_mut() {
-            alternative_grid.change_size(rows, columns);
-        }
     }
-
     pub fn read_buffer_as_lines(&self) -> Vec<Vec<TerminalCharacter>> {
         self.grid.as_character_lines()
     }
@@ -346,328 +324,4 @@ impl TerminalPane {
         // (x, y)
         self.grid.cursor_coordinates()
     }
-    pub fn rotate_scroll_region_up(&mut self, count: usize) {
-        self.grid.rotate_scroll_region_up(count);
-        self.mark_for_rerender();
-    }
-    pub fn rotate_scroll_region_down(&mut self, count: usize) {
-        self.grid.rotate_scroll_region_down(count);
-        self.mark_for_rerender();
-    }
-    fn reset_terminal_state(&mut self) {
-        let rows = self.get_rows();
-        let columns = self.get_columns();
-        self.grid = Grid::new(rows, columns);
-        self.alternative_grid = None;
-        self.cursor_key_mode = false;
-    }
-    fn add_newline(&mut self) {
-        let pad_character = EMPTY_TERMINAL_CHARACTER;
-        self.grid.add_canonical_line(pad_character);
-        self.mark_for_rerender();
-    }
-    fn move_to_beginning_of_line(&mut self) {
-        self.grid.move_cursor_to_beginning_of_line();
-    }
-    fn move_cursor_backwards(&mut self, count: usize) {
-        self.grid.move_cursor_backwards(count);
-    }
-    fn _reset_all_ansi_codes(&mut self) {
-        self.pending_styles.clear();
-    }
-}
-
-impl vte::Perform for TerminalPane {
-    fn print(&mut self, c: char) {
-        // apparently, building TerminalCharacter like this without a "new" method
-        // is a little faster
-        let terminal_character = TerminalCharacter {
-            character: c,
-            styles: self.pending_styles,
-        };
-        self.grid.add_character(terminal_character);
-    }
-
-    fn execute(&mut self, byte: u8) {
-        match byte {
-            8 => {
-                // backspace
-                self.move_cursor_backwards(1);
-            }
-            9 => {
-                // tab
-                self.grid.advance_to_next_tabstop(self.pending_styles);
-            }
-            10 => {
-                // 0a, newline
-                self.add_newline();
-            }
-            13 => {
-                // 0d, carriage return
-                self.move_to_beginning_of_line();
-            }
-            _ => {}
-        }
-    }
-
-    fn hook(&mut self, _params: &[i64], _intermediates: &[u8], _ignore: bool, _c: char) {
-        // TBD
-    }
-
-    fn put(&mut self, _byte: u8) {
-        // TBD
-    }
-
-    fn unhook(&mut self) {
-        // TBD
-    }
-
-    fn osc_dispatch(&mut self, _params: &[&[u8]], _bell_terminated: bool) {
-        // TBD
-    }
-
-    fn csi_dispatch(&mut self, params: &[i64], _intermediates: &[u8], _ignore: bool, c: char) {
-        if c == 'm' {
-            self.pending_styles.add_style_from_ansi_params(params);
-        } else if c == 'C' {
-            // move cursor forward
-            let move_by = if params[0] == 0 {
-                1
-            } else {
-                params[0] as usize
-            };
-            self.grid.move_cursor_forward_until_edge(move_by);
-        } else if c == 'K' {
-            // clear line (0 => right, 1 => left, 2 => all)
-            if params[0] == 0 {
-                let mut char_to_replace = EMPTY_TERMINAL_CHARACTER;
-                char_to_replace.styles = self.pending_styles;
-                self.grid
-                    .replace_characters_in_line_after_cursor(char_to_replace);
-            } else if params[0] == 1 {
-                let mut char_to_replace = EMPTY_TERMINAL_CHARACTER;
-                char_to_replace.styles = self.pending_styles;
-                self.grid
-                    .replace_characters_in_line_before_cursor(char_to_replace);
-            } else if params[0] == 2 {
-                self.grid.clear_cursor_line();
-            }
-        } else if c == 'J' {
-            // clear all (0 => below, 1 => above, 2 => all, 3 => saved)
-            let mut char_to_replace = EMPTY_TERMINAL_CHARACTER;
-            char_to_replace.styles = self.pending_styles;
-            if params[0] == 0 {
-                self.grid.clear_all_after_cursor(char_to_replace);
-            } else if params[0] == 2 {
-                self.grid.clear_all(char_to_replace);
-            }
-        // TODO: implement 1
-        } else if c == 'H' {
-            // goto row/col
-            // we subtract 1 from the row/column because these are 1 indexed
-            // (except when they are 0, in which case they should be 1
-            // don't look at me, I don't make the rules)
-            let (row, col) = if params.len() == 1 {
-                if params[0] == 0 {
-                    (0, params[0] as usize)
-                } else {
-                    (params[0] as usize - 1, params[0] as usize)
-                }
-            } else if params[0] == 0 {
-                (0, params[1] as usize - 1)
-            } else {
-                (params[0] as usize - 1, params[1] as usize - 1)
-            };
-            let pad_character = EMPTY_TERMINAL_CHARACTER;
-            self.grid.move_cursor_to(col, row, pad_character);
-        } else if c == 'A' {
-            // move cursor up until edge of screen
-            let move_up_count = if params[0] == 0 { 1 } else { params[0] };
-            self.grid.move_cursor_up(move_up_count as usize);
-        } else if c == 'B' {
-            // move cursor down until edge of screen
-            let move_down_count = if params[0] == 0 { 1 } else { params[0] };
-            let pad_character = EMPTY_TERMINAL_CHARACTER;
-            self.grid
-                .move_cursor_down(move_down_count as usize, pad_character);
-        } else if c == 'D' {
-            let move_back_count = if params[0] == 0 {
-                1
-            } else {
-                params[0] as usize
-            };
-            self.grid.move_cursor_back(move_back_count);
-        } else if c == 'l' {
-            let first_intermediate_is_questionmark = match _intermediates.get(0) {
-                Some(b'?') => true,
-                None => false,
-                _ => false,
-            };
-            if first_intermediate_is_questionmark {
-                match params.get(0) {
-                    Some(&1049) => {
-                        if let Some(alternative_grid) = self.alternative_grid.as_mut() {
-                            std::mem::swap(&mut self.grid, alternative_grid);
-                        }
-                        self.alternative_grid = None;
-                        self.clear_viewport_before_rendering = true;
-                        self.mark_for_rerender();
-                    }
-                    Some(&25) => {
-                        self.grid.hide_cursor();
-                        self.mark_for_rerender();
-                    }
-                    Some(&1) => {
-                        self.cursor_key_mode = false;
-                    }
-                    _ => {}
-                };
-            }
-        } else if c == 'h' {
-            let first_intermediate_is_questionmark = match _intermediates.get(0) {
-                Some(b'?') => true,
-                None => false,
-                _ => false,
-            };
-            if first_intermediate_is_questionmark {
-                match params.get(0) {
-                    Some(&25) => {
-                        self.grid.show_cursor();
-                        self.mark_for_rerender();
-                    }
-                    Some(&1049) => {
-                        let columns = self
-                            .position_and_size_override
-                            .map(|x| x.columns)
-                            .unwrap_or(self.position_and_size.columns);
-                        let rows = self
-                            .position_and_size_override
-                            .map(|x| x.rows)
-                            .unwrap_or(self.position_and_size.rows);
-                        let current_grid =
-                            std::mem::replace(&mut self.grid, Grid::new(rows, columns));
-                        self.alternative_grid = Some(current_grid);
-                        self.clear_viewport_before_rendering = true;
-                    }
-                    Some(&1) => {
-                        self.cursor_key_mode = true;
-                    }
-                    _ => {}
-                };
-            }
-        } else if c == 'r' {
-            if params.len() > 1 {
-                // minus 1 because these are 1 indexed
-                let top_line_index = params[0] as usize - 1;
-                let bottom_line_index = params[1] as usize - 1;
-                self.grid
-                    .set_scroll_region(top_line_index, bottom_line_index);
-                self.grid.show_cursor();
-            } else {
-                self.grid.clear_scroll_region();
-            }
-        } else if c == 't' {
-            // TBD - title?
-        } else if c == 'n' {
-            // TBD - device status report
-        } else if c == 'c' {
-            // TBD - identify terminal
-        } else if c == 'M' {
-            // delete lines if currently inside scroll region
-            let line_count_to_delete = if params[0] == 0 {
-                1
-            } else {
-                params[0] as usize
-            };
-            let pad_character = EMPTY_TERMINAL_CHARACTER;
-            self.grid
-                .delete_lines_in_scroll_region(line_count_to_delete, pad_character);
-        } else if c == 'L' {
-            // insert blank lines if inside scroll region
-            let line_count_to_add = if params[0] == 0 {
-                1
-            } else {
-                params[0] as usize
-            };
-            let pad_character = EMPTY_TERMINAL_CHARACTER;
-            self.grid
-                .add_empty_lines_in_scroll_region(line_count_to_add, pad_character);
-        } else if c == 'q' {
-            // ignore for now to run on mac
-        } else if c == 'G' {
-            let column = if params[0] == 0 {
-                0
-            } else {
-                params[0] as usize - 1
-            };
-            self.grid.move_cursor_to_column(column);
-        } else if c == 'd' {
-            // goto line
-            let line = if params[0] == 0 {
-                1
-            } else {
-                // minus 1 because this is 1 indexed
-                params[0] as usize - 1
-            };
-            let pad_character = EMPTY_TERMINAL_CHARACTER;
-            self.grid.move_cursor_to_line(line, pad_character);
-        } else if c == 'P' {
-            // erase characters
-            let count = if params[0] == 0 {
-                1
-            } else {
-                params[0] as usize
-            };
-            self.grid.erase_characters(count, self.pending_styles);
-        } else if c == 'X' {
-            // erase characters and replace with empty characters of current style
-            let count = if params[0] == 0 {
-                1
-            } else {
-                params[0] as usize
-            };
-            self.grid
-                .replace_with_empty_chars(count, self.pending_styles);
-        } else if c == 'T' {
-            /*
-             * 124  54  T   SD
-             * Scroll down, new lines inserted at top of screen
-             * [4T = Scroll down 4, bring previous lines back into view
-             */
-            let line_count: i64 = *params.get(0).expect("A number of lines was expected.");
-
-            if line_count >= 0 {
-                self.rotate_scroll_region_up(line_count as usize);
-            } else {
-                self.rotate_scroll_region_down(line_count.abs() as usize);
-            }
-        } else if c == 'S' {
-            // move scroll up
-            let count = if params[0] == 0 {
-                1
-            } else {
-                params[0] as usize
-            };
-            let pad_character = EMPTY_TERMINAL_CHARACTER;
-            self.grid
-                .delete_lines_in_scroll_region(count, pad_character);
-            // TODO: since delete_lines_in_scroll_region also adds lines, is the below redundant?
-            self.grid
-                .add_empty_lines_in_scroll_region(count, pad_character);
-        } else {
-            let _ = debug_log_to_file(format!("Unhandled csi: {}->{:?}", c, params));
-        }
-    }
-
-    fn esc_dispatch(&mut self, intermediates: &[u8], _ignore: bool, byte: u8) {
-        match (byte, intermediates.get(0)) {
-            (b'M', None) => {
-                self.grid.move_cursor_up_with_scrolling(1);
-            }
-            (b'c', None) => {
-                self.reset_terminal_state();
-            }
-            _ => {}
-        }
-    }
 }
diff --git a/src/client/tab.rs b/src/client/tab.rs
index 35fc3915..656c6093 100644
--- a/src/client/tab.rs
+++ b/src/client/tab.rs
@@ -20,7 +20,10 @@ use std::{io::Write, sync::mpsc::channel};
 use zellij_tile::data::{colors, Event, InputMode, ModeInfo, Palette};
 
 const CURSOR_HEIGHT_WIDTH_RATIO: usize = 4; // this is not accurate and kind of a magic number, TODO: look into this
-const MIN_TERMINAL_HEIGHT: usize = 2;
+
+// MIN_TERMINAL_HEIGHT here must be larger than the height of any of the status bars
+// this is a dirty hack until we implement fixed panes
+const MIN_TERMINAL_HEIGHT: usize = 3;
 const MIN_TERMINAL_WIDTH: usize = 4;
 
 type BorderAndPaneIds = (usize, Vec<PaneId>);
@@ -67,7 +70,6 @@ pub struct Tab {
     pub send_pty_instructions: SenderWithContext<PtyInstruction>,
     pub send_plugin_instructions: SenderWithContext<PluginInstruction>,
     pub send_app_instructions: SenderWithContext<AppInstruction>,
-    expansion_boundary: Option<PositionAndSize>,
     should_clear_display_before_rendering: bool,
     pub mode_info: ModeInfo,
     pub input_mode: InputMode,
@@ -208,6 +210,7 @@ pub trait Pane {
 
 impl Tab {
     // FIXME: Too many arguments here! Maybe bundle all of the senders for the whole program in a struct?
+    #[allow(clippy::too_many_arguments)]
     pub fn new(
         index: usize,
         position: usize,
@@ -250,7 +253,6 @@ impl Tab {
             send_app_instructions,
             send_pty_instructions,
             send_plugin_instructions,
-            expansion_boundary: None,
             should_clear_display_before_rendering: false,
             mode_info,
             input_mode,
@@ -293,9 +295,6 @@ impl Tab {
         let mut new_pids = new_pids.iter();
         for (layout, position_and_size) in positions_and_size {
             // Just a regular terminal
-            if layout.expansion_boundary {
-                self.expansion_boundary = Some(*position_and_size);
-            }
             if let Some(plugin) = &layout.plugin {
                 let (pid_tx, pid_rx) = channel();
                 self.send_plugin_instructions
@@ -365,9 +364,7 @@ impl Tab {
                     let (id_of_terminal_to_check, terminal_to_check) = id_and_terminal_to_check;
                     let terminal_size = (terminal_to_check.rows() * CURSOR_HEIGHT_WIDTH_RATIO)
                         * terminal_to_check.columns();
-                    let terminal_pos_and_size = terminal_to_check.position_and_size();
                     let terminal_can_be_split = terminal_to_check.columns() >= MIN_TERMINAL_WIDTH
-                        && self.pos_and_size_is_within_expansion_boundary(terminal_pos_and_size)
                         && terminal_to_check.rows() >= MIN_TERMINAL_HEIGHT
                         && ((terminal_to_check.columns() > terminal_to_check.min_width() * 2)
                             || (terminal_to_check.rows() > terminal_to_check.min_height() * 2));
@@ -627,19 +624,17 @@ impl Tab {
                 let active_terminal = self.panes.get_mut(&active_pane_id).unwrap();
                 active_terminal.reset_size_and_position_override();
             } else {
-                let expand_to = self.expansion_boundary.unwrap_or(self.full_screen_ws);
                 let panes = self.get_panes();
-                let pane_ids_to_hide = panes.filter_map(|(&id, pane)| {
-                    let position_and_size_for_pane = pane.position_and_size();
-                    if id != active_pane_id
-                        && self
-                            .pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    {
-                        Some(id)
-                    } else {
-                        None
-                    }
-                });
+                let pane_ids_to_hide =
+                    panes.filter_map(
+                        |(&id, _)| {
+                            if id != active_pane_id {
+                                Some(id)
+                            } else {
+                                None
+                            }
+                        },
+                    );
                 self.panes_to_hide = pane_ids_to_hide.collect();
                 if self.panes_to_hide.is_empty() {
                     // nothing to do, pane is already as fullscreen as it can be, let's bail
@@ -647,9 +642,9 @@ impl Tab {
                 } else {
                     let active_terminal = self.panes.get_mut(&active_pane_id).unwrap();
                     active_terminal.override_size_and_position(
-                        expand_to.x,
-                        expand_to.y,
-                        &expand_to,
+                        self.full_screen_ws.x,
+                        self.full_screen_ws.y,
+                        &self.full_screen_ws,
                     );
                 }
             }
@@ -1503,21 +1498,6 @@ impl Tab {
             self.increase_pane_width_left(&terminal_id, count);
         }
     }
-    fn pos_and_size_is_within_expansion_boundary(&self, pos_and_size: PositionAndSize) -> bool {
-        match self.expansion_boundary {
-            Some(expansion_boundary) => {
-                pos_and_size.x >= expansion_boundary.x
-                    && pos_and_size.x < expansion_boundary.x + expansion_boundary.columns
-                    && pos_and_size.y >= expansion_boundary.y
-                    && pos_and_size.y < expansion_boundary.y + expansion_boundary.rows
-                    && pos_and_size.x + pos_and_size.columns
-                        <= expansion_boundary.x + expansion_boundary.columns
-                    && pos_and_size.y + pos_and_size.rows
-                        <= expansion_boundary.y + expansion_boundary.rows
-            }
-            None => true, // no expansion boundary, no problem
-        }
-    }
     fn can_increase_pane_and_surroundings_right(
         &self,
         pane_id: &PaneId,
@@ -1533,17 +1513,11 @@ impl Tab {
         }
         let mut new_pos_and_size_for_pane = pane.position_and_size();
         new_pos_and_size_for_pane.columns += increase_by;
-        if !self.pos_and_size_is_within_expansion_boundary(new_pos_and_size_for_pane) {
-            return false;
-        }
 
         if let Some(panes_to_the_right) = self.pane_ids_directly_right_of(&pane_id) {
             return panes_to_the_right.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.columns() > increase_by
-                    && p.columns() - increase_by >= p.min_width()
+                p.columns() > increase_by && p.columns() - increase_by >= p.min_width()
             });
         } else {
             false
@@ -1564,17 +1538,11 @@ impl Tab {
         }
         let mut new_pos_and_size_for_pane = pane.position_and_size();
         new_pos_and_size_for_pane.x = new_pos_and_size_for_pane.x.saturating_sub(increase_by);
-        if !self.pos_and_size_is_within_expansion_boundary(new_pos_and_size_for_pane) {
-            return false;
-        }
 
         if let Some(panes_to_the_left) = self.pane_ids_directly_left_of(&pane_id) {
             return panes_to_the_left.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.columns() > increase_by
-                    && p.columns() - increase_by >= p.min_width()
+                p.columns() > increase_by && p.columns() - increase_by >= p.min_width()
             });
         } else {
             false
@@ -1595,17 +1563,11 @@ impl Tab {
         }
         let mut new_pos_and_size_for_pane = pane.position_and_size();
         new_pos_and_size_for_pane.rows += increase_by;
-        if !self.pos_and_size_is_within_expansion_boundary(new_pos_and_size_for_pane) {
-            return false;
-        }
 
         if let Some(panes_below) = self.pane_ids_directly_below(&pane_id) {
             return panes_below.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.rows() > increase_by
-                    && p.rows() - increase_by >= p.min_height()
+                p.rows() > increase_by && p.rows() - increase_by >= p.min_height()
             });
         } else {
             false
@@ -1622,17 +1584,11 @@ impl Tab {
         }
         let mut new_pos_and_size_for_pane = pane.position_and_size();
         new_pos_and_size_for_pane.y = new_pos_and_size_for_pane.y.saturating_sub(increase_by);
-        if !self.pos_and_size_is_within_expansion_boundary(new_pos_and_size_for_pane) {
-            return false;
-        }
 
         if let Some(panes_above) = self.pane_ids_directly_above(&pane_id) {
             return panes_above.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.rows() > increase_by
-                    && p.rows() - increase_by >= p.min_height()
+                p.rows() > increase_by && p.rows() - increase_by >= p.min_height()
             });
         } else {
             false
@@ -1649,11 +1605,9 @@ impl Tab {
         if let Some(panes_to_the_left) = self.pane_ids_directly_left_of(&pane_id) {
             return panes_to_the_left.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.max_width()
-                        .map(|max_width| p.columns() + reduce_by <= max_width)
-                        .unwrap_or(true) // no max width, increase to your heart's content
+                p.max_width()
+                    .map(|max_width| p.columns() + reduce_by <= max_width)
+                    .unwrap_or(true) // no max width, increase to your heart's content
             });
         } else {
             false
@@ -1670,11 +1624,9 @@ impl Tab {
         if let Some(panes_to_the_right) = self.pane_ids_directly_right_of(&pane_id) {
             return panes_to_the_right.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.max_width()
-                        .map(|max_width| p.columns() + reduce_by <= max_width)
-                        .unwrap_or(true) // no max width, increase to your heart's content
+                p.max_width()
+                    .map(|max_width| p.columns() + reduce_by <= max_width)
+                    .unwrap_or(true) // no max width, increase to your heart's content
             });
         } else {
             false
@@ -1691,11 +1643,9 @@ impl Tab {
         if let Some(panes_above) = self.pane_ids_directly_above(&pane_id) {
             return panes_above.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.max_height()
-                        .map(|max_height| p.rows() + reduce_by <= max_height)
-                        .unwrap_or(true) // no max height, increase to your heart's content
+                p.max_height()
+                    .map(|max_height| p.rows() + reduce_by <= max_height)
+                    .unwrap_or(true) // no max height, increase to your heart's content
             });
         } else {
             false
@@ -1712,11 +1662,9 @@ impl Tab {
         if let Some(panes_below) = self.pane_ids_directly_below(&pane_id) {
             return panes_below.iter().all(|id| {
                 let p = self.panes.get(id).unwrap();
-                let position_and_size_for_pane = p.position_and_size();
-                self.pos_and_size_is_within_expansion_boundary(position_and_size_for_pane)
-                    && p.max_height()
-                        .map(|max_height| p.rows() + reduce_by <= max_height)
-                        .unwrap_or(true) // no max height, increase to your heart's content
+                p.max_height()
+                    .map(|max_height| p.rows() + reduce_by <= max_height)
+                    .unwrap_or(true) // no max height, increase to your heart's content
             });
         } else {
             false
@@ -1724,27 +1672,18 @@ impl Tab {
     }
     pub fn resize_whole_tab(&mut self, new_screen_size: PositionAndSize) {
         if self.fullscreen_is_active {
-            // this is not ideal but until we get rid of expansion_boundary, it's a necessity
+            // this is not ideal, we can improve this
             self.toggle_active_pane_fullscreen();
         }
-        match PaneResizer::new(&mut self.panes, &mut self.os_api)
-            .resize(self.full_screen_ws, new_screen_size)
+        if let Some((column_difference, row_difference)) =
+            PaneResizer::new(&mut self.panes, &mut self.os_api)
+                .resize(self.full_screen_ws, new_screen_size)
         {
-            Some((column_difference, row_difference)) => {
-                self.should_clear_display_before_rendering = true;
-                self.expansion_boundary.as_mut().map(|expansion_boundary| {
-                    // TODO: this is not always accurate
-                    expansion_boundary.columns =
-                        (expansion_boundary.columns as isize + column_difference) as usize;
-                    expansion_boundary.rows =
-                        (expansion_boundary.rows as isize + row_difference) as usize;
-                });
-                self.full_screen_ws.columns =
-                    (self.full_screen_ws.columns as isize + column_difference) as usize;
-                self.full_screen_ws.rows =
-                    (self.full_screen_ws.rows as isize + row_difference) as usize;
-            }
-            None => {}
+            self.should_clear_display_before_rendering = true;
+            self.full_screen_ws.columns =
+                (self.full_screen_ws.columns as isize + column_difference) as usize;
+            self.full_screen_ws.rows =
+                (self.full_screen_ws.rows as isize + row_difference) as usize;
         };
     }
     pub fn resize_left(&mut self) {
@@ -2242,6 +2181,30 @@ impl Tab {
             self.render();
         }
     }
+    pub fn scroll_active_terminal_up_page(&mut self) {
+        if let Some(active_terminal_id) = self.get_active_terminal_id() {
+            let active_terminal = self
+                .panes
+                .get_mut(&PaneId::Terminal(active_terminal_id))
+                .unwrap();
+            // prevent overflow when row == 0
+            let scroll_columns = active_terminal.rows().max(1) - 1;
+            active_terminal.scroll_up(scroll_columns);
+            self.render();
+        }
+    }
+    pub fn scroll_active_terminal_down_page(&mut self) {
+        if let Some(active_terminal_id) = self.get_active_terminal_id() {
+            let active_terminal = self
+                .panes
+                .get_mut(&PaneId::Terminal(active_terminal_id))
+                .unwrap();
+            // prevent overflow when row == 0
+            let scroll_columns = active_terminal.rows().max(1) - 1;
+            active_terminal.scroll_down(scroll_columns);
+            self.render();
+        }
+    }
     pub fn clear_active_terminal_scroll(&mut self) {
         if let Some(active_terminal_id) = self.get_active_terminal_id() {
             let active_terminal = self