adjust_window_size_when_changing_font_size now considers tiling WMs

It's a little limited in the scope of its detection: we have a built-in
list of tiling WM environments and if the current one is on the list
then we set an appropriate value for this option.

The list currently has just a single entry.

config/src/config.rs

@@ -688,8 +688,11 @@ pub struct Config {
     #[dynamic(default = "default_enq_answerback")]
     pub enq_answerback: String,
 
-    #[dynamic(default = "default_true")]
-    pub adjust_window_size_when_changing_font_size: bool,
+    #[dynamic(default)]
+    pub adjust_window_size_when_changing_font_size: Option<bool>,
+
+    #[dynamic(default = "default_tiling_desktop_environments")]
+    pub tiling_desktop_environments: Vec<String>,
 
     #[dynamic(default)]
     pub use_resize_increments: bool,
@@ -1673,6 +1676,10 @@ fn default_max_fps() -> u8 {
     60
 }
 
+fn default_tiling_desktop_environments() -> Vec<String> {
+    ["X11 bspwm"].iter().map(|s| s.to_string()).collect()
+}
+
 fn default_stateless_process_list() -> Vec<String> {
     [
         "bash",

docs/changelog.md

@@ -24,6 +24,10 @@ As features stabilize some brief notes about them will accumulate here.
 #### Changed
 
 * The default for [front_end](config/lua/config/front_end.md) is now `WebGpu`.
+* The default for
+  [adjust_window_size_when_changing_font_size](config/lua/config/adjust_window_size_when_changing_font_size.md)
+  now depends on the window environment and the contents of
+  [tiling_desktop_environments](config/lua/config/tiling_desktop_environments.md).
 
 #### New
 

docs/config/lua/config/adjust_window_size_when_changing_font_size.md

@@ -15,3 +15,12 @@ If you use a tiling window manager then you may wish to set this to `false`.
 
 See also [IncreaseFontSize](../keyassignment/IncreaseFontSize.md),
 [DecreaseFontSize](../keyassignment/DecreaseFontSize.md).
+
+{{since('nightly')}}
+
+The default value is now `nil` which causes wezterm to match the name of the
+connected window environment (which you can see if you open the debug overlay)
+against the list of known tiling environments configured by
+[tiling_desktop_environments](tiling_desktop_environments.md).  If the
+environment is known to be tiling then the effective value of
+`adjust_window_size_when_changing_font_size` is `false`, and `true` otherwise.

docs/config/lua/config/tiling_desktop_environments.md

@@ -0,0 +1,32 @@
+# `tiling_desktop_environments = {}`
+
+{{since('nightly')}}
+
+Contains a list of Window Environments that are known to be tiling
+window managers. A tiling window manager is one that automatically
+resizes windows according to some layout policy, rather than respecting
+the window size set by an application.
+
+The default value for this option is:
+
+```lua
+config.tiling_desktop_environments = {
+  'X11 bspwm',
+}
+```
+
+The environment name can be found in the debug overlay which you can show via
+the [ShowDebugOverlay](../keyassignment/ShowDebugOverlay.md) key assignment.
+The default key binding for it is <kbd>Ctrl</kbd> + <kbd>Shift</kbd> +
+<kbd>L</kbd>.
+
+Look for the line beginning with `Window Environment:`. The text after the
+colon is the name to add to `tiling_desktop_environments`.
+
+If your window environment is a tiling environment and is not listed
+here, please file an issue (or even a PR!) to add it to the default
+list.
+
+This contents of this list are used to determine a reasonable default for
+[adjust_window_size_when_changing_font_size](adjust_window_size_when_changing_font_size.md).
+

wezterm-gui/src/termwindow/mod.rs

@@ -444,6 +444,8 @@ pub struct TermWindow {
     num_frames: usize,
     pub fps: f32,
 
+    connection_name: String,
+
     gl: Option<Rc<glium::backend::Context>>,
     webgpu: Option<Rc<WebGpuState>>,
     config_subscription: Option<config::ConfigSubscription>,
@@ -659,8 +661,11 @@ impl TermWindow {
 
         let render_state = None;
 
+        let connection_name = Connection::get().unwrap().name();
+
         let myself = Self {
             created: Instant::now(),
+            connection_name,
             last_fps_check_time: Instant::now(),
             num_frames: 0,
             last_frame_duration: Duration::ZERO,
@@ -1606,6 +1611,7 @@ impl TermWindow {
             self.config_overrides
         );
         self.key_table_state.clear_stack();
+        self.connection_name = Connection::get().unwrap().name();
         let config = match config::overridden_config(&self.config_overrides) {
             Ok(config) => config,
             Err(err) => {
@@ -2205,7 +2211,7 @@ impl TermWindow {
         let gui_win = GuiWin::new(self);
 
         let opengl_info = self.opengl_info.as_deref().unwrap_or("Unknown").to_string();
-        let connection_info = Connection::get().unwrap().name();
+        let connection_info = self.connection_name.clone();
 
         let (overlay, future) = start_overlay(self, &tab, move |_tab_id, term| {
             crate::overlay::show_debug_overlay(term, gui_win, opengl_info, connection_info)

wezterm-gui/src/termwindow/resize.rs

@@ -385,8 +385,20 @@ impl super::TermWindow {
     /// the `adjust_window_size_when_changing_font_size` configuration and
     /// revises the scaling/resize change accordingly
     pub fn adjust_font_scale(&mut self, font_scale: f64, window: &Window) {
-        if self.window_state.can_resize() && self.config.adjust_window_size_when_changing_font_size
-        {
+        let adjust_window_size_when_changing_font_size =
+            match self.config.adjust_window_size_when_changing_font_size {
+                Some(value) => value,
+                None => {
+                    let is_tiling = self
+                        .config
+                        .tiling_desktop_environments
+                        .iter()
+                        .any(|item| item.as_str() == self.connection_name.as_str());
+                    !is_tiling
+                }
+            };
+
+        if self.window_state.can_resize() && adjust_window_size_when_changing_font_size {
             self.scaling_changed(self.dimensions, font_scale, window);
         } else {
             let dimensions = self.dimensions;