Renamed timeout source and callback function. Added comment explaining timeout delay.

src/apprt/gtk/class/window.zig

@@ -221,7 +221,7 @@ pub const Window = extern struct {
         quick_terminal: bool = false,
 
         /// Timeout source to react to this window becoming (in)active.
-        timeout: ?c_uint = null,
+        handle_active_state_source: ?c_uint = null,
 
         /// The window decoration override. If this is not set then we'll
         /// inherit whatever the config has. This allows overriding the
@@ -858,10 +858,13 @@ pub const Window = extern struct {
         }
     }
 
-    fn onTimeout(ud: ?*anyopaque) callconv(.c) c_int {
+    /// Callback to handle this window becoming active or inactive.
+    /// Triggered by propIsActive with a timeout to debounce temporary
+    /// changes in active state.
+    fn handleActiveState(ud: ?*anyopaque) callconv(.c) c_int {
         const self: *Self = @ptrCast(@alignCast(ud orelse return 0));
         const priv = self.private();
-        priv.timeout = null;
+        priv.handle_active_state_source = null;
 
         // Hide quick-terminal if set to autohide
         if (self.isQuickTerminal()) {
@@ -1113,12 +1116,29 @@ pub const Window = extern struct {
         // Use a timeout callback to wait for focus state to settle,
         // because depending on the windowing backend the window might
         // become inactive and immediately active again. This happens
-        // e.g. on Wayland when opening a context menu.
+        // e.g. on Wayland when opening a context menu or a submenu
-        if (priv.timeout == null) priv.timeout = glib.timeoutAdd(
+        // inside a context menu.
-            100,
+        if (priv.handle_active_state_source == null) {
-            onTimeout,
+            priv.handle_active_state_source = glib.timeoutAddFull(
-            self,
+                // Use priority of an idle callback instead of the higher
-        );
+                // default timeout priority. This allows us to use a shorter
+                // timeout duration.
+                glib.PRIORITY_DEFAULT_IDLE,
+                // 50ms was chosen to be conservative. From testing we know
+                // that, depending on the backend and system performance, a
+                // shorter timeout or just an idle callback can be enough for
+                // the focus to settle. On the other hand a delay of e.g. 10ms
+                // does not work reliably on some slow systems. The downside
+                // of a high value is that some operations in handleActiveState,
+                // e.g. hiding the quick-terminal, will be visibly delayed.
+                // However, 50ms should barely be noticeable. We can change
+                // this in the future if necessary.
+                50,
+                handleActiveState,
+                self,
+                null,
+            );
+        }
     }
 
     fn propGdkSurfaceDims(
@@ -1237,11 +1257,11 @@ pub const Window = extern struct {
     fn dispose(self: *Self) callconv(.c) void {
         const priv = self.private();
 
-        if (priv.timeout) |v| {
+        if (priv.handle_active_state_source) |v| {
             if (glib.Source.remove(v) == 0) {
-                log.warn("unable to remove timeout source", .{});
+                log.warn("unable to remove handle active state source", .{});
             }
-            priv.timeout = null;
+            priv.handle_active_state_source = null;
         }
 
         priv.command_palette.set(null);