feat(ui): pane frames (new pane UI) (#643)

* work

* resize working

* move focus working

* close pane working

* selection and fullscreen working

* pane title line

* titles and conditional scroll title

* whole tab resize working

* plugin frames working

* plugin splitting working

* truncate pane frame titles

* cleanup

* panes always draw their own borders - also fix gap

* toggle pane frames

* move toggle to screen and fix some bugs

* fix plugin frame toggle

* fix terminal window resize

* fix scrolling and fullscreen bugs

* unit tests passing

* e2e tests passing and new test for new frames added

* refactor: TerminalPane and PluginPane

* refactor: Tab

* refactor: moar Tab

* refactor: Boundaries

* only render and calculate boundaries when there are no pane frames

* refactor: Layout

* fix(grid): properly resize when coming back from alternative viewport

* style: remove commented code

* style: fmt

* style: fmt

* style: fmt + clippy

* docs(changelog): update change

11 files changed, 46 insertions, 8 deletions

diff --git a/zellij-utils/assets/config/default.yaml b/zellij-utils/assets/config/default.yaml
index 24ee95f59..4654cee90 100644
--- a/zellij-utils/assets/config/default.yaml
+++ b/zellij-utils/assets/config/default.yaml
@@ -105,6 +105,8 @@ keybinds:
           key: [Char: 'x',]
         - action: [ToggleFocusFullscreen,]
           key: [Char: 'f',]
+        - action: [TogglePaneFrames,]
+          key: [Char: 'z',]
         - action: [FocusPreviousPane,]
           key: [ Alt: '[',]
         - action: [FocusNextPane,]
diff --git a/zellij-utils/assets/layouts/default.yaml b/zellij-utils/assets/layouts/default.yaml
index 96bf1809c..b163821de 100644
--- a/zellij-utils/assets/layouts/default.yaml
+++ b/zellij-utils/assets/layouts/default.yaml
@@ -2,12 +2,14 @@
 direction: Horizontal
 parts:
   - direction: Vertical
+    borderless: true
     split_size:
       Fixed: 1
     run:
       plugin: tab-bar
   - direction: Vertical
   - direction: Vertical
+    borderless: true
     split_size:
       Fixed: 2
     run:
diff --git a/zellij-utils/assets/layouts/disable-status-bar.yaml b/zellij-utils/assets/layouts/disable-status-bar.yaml
index b990ba500..a03c71c3a 100644
--- a/zellij-utils/assets/layouts/disable-status-bar.yaml
+++ b/zellij-utils/assets/layouts/disable-status-bar.yaml
@@ -2,6 +2,7 @@
 direction: Horizontal
 parts:
   - direction: Vertical
+    borderless: true
     split_size:
       Fixed: 1
     run:
diff --git a/zellij-utils/assets/layouts/strider.yaml b/zellij-utils/assets/layouts/strider.yaml
index 9bbe5772f..288143894 100644
--- a/zellij-utils/assets/layouts/strider.yaml
+++ b/zellij-utils/assets/layouts/strider.yaml
@@ -2,6 +2,7 @@
 direction: Horizontal
 parts:
   - direction: Vertical
+    borderless: true
     split_size:
       Fixed: 1
     run:
@@ -15,6 +16,7 @@ parts:
           plugin: strider
       - direction: Horizontal
   - direction: Vertical
+    borderless: true
     split_size:
       Fixed: 2
     run:
diff --git a/zellij-utils/src/errors.rs b/zellij-utils/src/errors.rs
index 6a053038a..c0891d52d 100644
--- a/zellij-utils/src/errors.rs
+++ b/zellij-utils/src/errors.rs
@@ -209,6 +209,7 @@ pub enum ScreenContext {
     CloseFocusedPane,
     ToggleActiveSyncTab,
     ToggleActiveTerminalFullscreen,
+    TogglePaneFrames,
     SetSelectable,
     SetInvisibleBorders,
     SetFixedHeight,
diff --git a/zellij-utils/src/input/actions.rs b/zellij-utils/src/input/actions.rs
index 431a09bf7..3e86409bc 100644
--- a/zellij-utils/src/input/actions.rs
+++ b/zellij-utils/src/input/actions.rs
@@ -56,6 +56,8 @@ pub enum Action {
     PageScrollDown,
     /// Toggle between fullscreen focus pane and normal layout.
     ToggleFocusFullscreen,
+    /// Toggle frames around panes in the UI
+    TogglePaneFrames,
     /// Toggle between sending text commands to all panes on the current tab and normal mode.
     ToggleActiveSyncTab,
     /// Open a new pane in the specified direction (relative to focus).
diff --git a/zellij-utils/src/input/layout.rs b/zellij-utils/src/input/layout.rs
index 090ccb13f..33e08bfdb 100644
--- a/zellij-utils/src/input/layout.rs
+++ b/zellij-utils/src/input/layout.rs
@@ -50,6 +50,8 @@ pub struct Layout {
     pub parts: Vec<Layout>,
     pub split_size: Option<SplitSize>,
     pub run: Option<Run>,
+    #[serde(default)]
+    pub borderless: bool,
 }
 
 type LayoutResult = Result<Layout, ConfigError>;
@@ -141,6 +143,14 @@ impl Layout {
         total_panes
     }
 
+    pub fn total_borderless_panes(&self) -> usize {
+        let mut total_borderless_panes = 0;
+        total_borderless_panes += self.parts.iter().filter(|p| p.borderless).count();
+        for part in self.parts.iter() {
+            total_borderless_panes += part.total_borderless_panes();
+        }
+        total_borderless_panes
+    }
     pub fn extract_run_instructions(&self) -> Vec<Option<Run>> {
         let mut run_instructions = vec![];
         if self.parts.is_empty() {
@@ -168,7 +178,7 @@ fn split_space_to_parts_vertically(
     let mut split_parts = Vec::new();
     let mut current_x_position = space_to_split.x;
     let mut current_width = 0;
-    let max_width = space_to_split.cols - (sizes.len() - 1); // minus space for gaps
+    let max_width = space_to_split.cols;
 
     let mut parts_to_grow = Vec::new();
 
@@ -192,7 +202,7 @@ fn split_space_to_parts_vertically(
             ..Default::default()
         });
         current_width += columns;
-        current_x_position += columns + 1; // 1 for gap
+        current_x_position += columns;
     }
 
     if current_width > max_width {
@@ -210,7 +220,7 @@ fn split_space_to_parts_vertically(
                 last_flexible_index = idx;
             }
             current_width += part.cols;
-            current_x_position += part.cols + 1; // 1 for gap
+            current_x_position += part.cols;
         }
     }
 
@@ -233,7 +243,7 @@ fn split_space_to_parts_horizontally(
     let mut split_parts = Vec::new();
     let mut current_y_position = space_to_split.y;
     let mut current_height = 0;
-    let max_height = space_to_split.rows - (sizes.len() - 1); // minus space for gaps
+    let max_height = space_to_split.rows;
 
     let mut parts_to_grow = Vec::new();
 
@@ -256,7 +266,7 @@ fn split_space_to_parts_horizontally(
             ..Default::default()
         });
         current_height += rows;
-        current_y_position += rows + 1; // 1 for gap
+        current_y_position += rows;
     }
 
     if current_height > max_height {
@@ -275,7 +285,7 @@ fn split_space_to_parts_horizontally(
                 last_flexible_index = idx;
             }
             current_height += part.rows;
-            current_y_position += part.rows + 1; // 1 for gap
+            current_y_position += part.rows;
         }
     }
 
diff --git a/zellij-utils/src/input/mod.rs b/zellij-utils/src/input/mod.rs
index 746d58619..87d72db8a 100644
--- a/zellij-utils/src/input/mod.rs
+++ b/zellij-utils/src/input/mod.rs
@@ -30,6 +30,7 @@ pub fn get_mode_info(
             ("r".to_string(), "Right split".to_string()),
             ("x".to_string(), "Close".to_string()),
             ("f".to_string(), "Fullscreen".to_string()),
+            ("z".to_string(), "Frames".to_string()),
         ],
         InputMode::Tab => vec![
             ("←↓↑→".to_string(), "Move focus".to_string()),
diff --git a/zellij-utils/src/input/options.rs b/zellij-utils/src/input/options.rs
index a2f9231cd..94994e1e3 100644
--- a/zellij-utils/src/input/options.rs
+++ b/zellij-utils/src/input/options.rs
@@ -58,6 +58,9 @@ pub struct Options {
     #[serde(default)]
     /// Disable handling of mouse events
     pub disable_mouse_mode: bool,
+    #[structopt(long)]
+    #[serde(default)]
+    pub no_pane_frames: bool,
     /// Set behaviour on force close (quit or detach)
     #[structopt(long)]
     pub on_force_close: Option<OnForceClose>,
@@ -80,6 +83,7 @@ impl Options {
 
         let simplified_ui = merge_bool(other.simplified_ui, self.simplified_ui);
         let disable_mouse_mode = merge_bool(other.disable_mouse_mode, self.disable_mouse_mode);
+        let no_pane_frames = merge_bool(other.no_pane_frames, self.no_pane_frames);
 
         let default_mode = other.default_mode.or(self.default_mode);
         let default_shell = other.default_shell.or_else(|| self.default_shell.clone());
@@ -94,6 +98,7 @@ impl Options {
             default_shell,
             layout_dir,
             disable_mouse_mode,
+            no_pane_frames,
             on_force_close,
         }
     }
diff --git a/zellij-utils/src/pane_size.rs b/zellij-utils/src/pane_size.rs
index da165d4e6..db439b612 100644
--- a/zellij-utils/src/pane_size.rs
+++ b/zellij-utils/src/pane_size.rs
@@ -5,7 +5,7 @@ use crate::position::Position;
 
 /// Contains the position and size of a [`Pane`], or more generally of any terminal, measured
 /// in character rows and columns.
-#[derive(Clone, Copy, Debug, Default, Serialize, Deserialize)]
+#[derive(Clone, Copy, Debug, Default, Serialize, Deserialize, PartialEq, Eq)]
 pub struct PositionAndSize {
     pub x: usize,
     pub y: usize,
@@ -34,4 +34,16 @@ impl PositionAndSize {
         let row = point.line.0 as usize;
         self.x <= col && col < self.x + self.cols && self.y <= row && row < self.y + self.rows
     }
+    pub fn reduce_outer_frame(mut self, frame_width: usize) -> Self {
+        self.x += frame_width;
+        self.rows -= frame_width * 2;
+        self.y += frame_width;
+        self.cols -= frame_width * 2;
+        self
+    }
+    pub fn reduce_top_line(mut self) -> Self {
+        self.y += 1;
+        self.rows -= 1;
+        self
+    }
 }
diff --git a/zellij-utils/src/shared.rs b/zellij-utils/src/shared.rs
index a741cc10b..b1edb97fd 100644
--- a/zellij-utils/src/shared.rs
+++ b/zellij-utils/src/shared.rs
@@ -18,7 +18,7 @@ pub fn set_permissions(path: &Path) -> io::Result<()> {
     fs::set_permissions(path, permissions)
 }
 
-fn ansi_len(s: &str) -> usize {
+pub fn ansi_len(s: &str) -> usize {
     from_utf8(&strip(s.as_bytes()).unwrap())
         .unwrap()
         .chars()