Add default-column-display window rule

niri-config/src/lib.rs

@@ -1113,6 +1113,8 @@ pub struct WindowRule {
     pub block_out_from: Option<BlockOutFrom>,
     #[knuffel(child, unwrap(argument))]
     pub variable_refresh_rate: Option<bool>,
+    #[knuffel(child, unwrap(argument, str))]
+    pub default_column_display: Option<ColumnDisplay>,
     #[knuffel(child)]
     pub default_floating_position: Option<FloatingPosition>,
     #[knuffel(child, unwrap(argument))]
@@ -3557,6 +3559,7 @@ mod tests {
                 open-floating false
                 open-focused true
                 default-window-height { fixed 500; }
+                default-column-display "tabbed"
                 default-floating-position x=100 y=-200 relative-to="bottom-left"
 
                 focus-ring {
@@ -3856,6 +3859,7 @@ mod tests {
                     open_floating: Some(false),
                     open_focused: Some(true),
                     default_window_height: Some(DefaultPresetSize(Some(PresetSize::Fixed(500)))),
+                    default_column_display: Some(ColumnDisplay::Tabbed),
                     default_floating_position: Some(FloatingPosition {
                         x: FloatOrInt(100.),
                         y: FloatOrInt(-200.),

src/layout/scrolling.rs

@@ -3253,6 +3253,12 @@ impl<W: LayoutElement> Column<W> {
     ) -> Self {
         let options = tile.options.clone();
 
+        let display_mode = tile
+            .window()
+            .rules()
+            .default_column_display
+            .unwrap_or(options.default_column_display);
+
         let mut rv = Self {
             tiles: vec![],
             data: vec![],
@@ -3261,7 +3267,7 @@ impl<W: LayoutElement> Column<W> {
             preset_width_idx: None,
             is_full_width,
             is_fullscreen: false,
-            display_mode: options.default_column_display,
+            display_mode,
             move_animation: None,
             view_size,
             working_area,

src/window/mod.rs

@@ -4,6 +4,7 @@ use niri_config::{
     BlockOutFrom, BorderRule, CornerRadius, FloatingPosition, Match, PresetSize, ShadowRule,
     WindowRule,
 };
+use niri_ipc::ColumnDisplay;
 use smithay::reexports::wayland_protocols::xdg::shell::server::xdg_toplevel;
 use smithay::utils::{Logical, Size};
 use smithay::wayland::compositor::with_states;
@@ -43,6 +44,9 @@ pub struct ResolvedWindowRules {
     /// - `Some(Some(height))`: set to a particular height.
     pub default_height: Option<Option<PresetSize>>,
 
+    /// Default column display for this window.
+    pub default_column_display: Option<ColumnDisplay>,
+
     /// Default floating position for this window.
     pub default_floating_position: Option<FloatingPosition>,
 
@@ -147,6 +151,7 @@ impl ResolvedWindowRules {
         Self {
             default_width: None,
             default_height: None,
+            default_column_display: None,
             default_floating_position: None,
             open_on_output: None,
             open_on_workspace: None,
@@ -237,6 +242,10 @@ impl ResolvedWindowRules {
                     resolved.default_height = Some(x.0);
                 }
 
+                if let Some(x) = rule.default_column_display {
+                    resolved.default_column_display = Some(x);
+                }
+
                 if let Some(x) = rule.default_floating_position {
                     resolved.default_floating_position = Some(x);
                 }

wiki/Configuration:-Window-Rules.md

@@ -52,6 +52,7 @@ window-rule {
     block-out-from "screencast"
     // block-out-from "screen-capture"
     variable-refresh-rate true
+    default-column-display "tabbed"
     default-floating-position x=100 y=200 relative-to="bottom-left"
     scroll-factor 0.75
 
@@ -528,6 +529,27 @@ window-rule {
 }
 ```
 
+#### `default-column-display`
+
+<sup>Since: next release</sup>
+
+Set the default display mode for columns created from this window.
+
+This is used any time a window goes into its own column.
+For example:
+- Opening a new window.
+- Expelling a window into its own column.
+- Moving a window from the floating layout to the tiling layout.
+
+```kdl
+// Make Evince windows open as tabbed columns.
+window-rule {
+    match app-id="^evince$"
+
+    default-column-display "tabbed"
+}
+```
+
 #### `default-floating-position`
 
 <sup>Since: 25.01</sup>