window: Make default focus window on each workspace appear focused

Makes workspace transitions in gnome-shell look more seamless, since
both outgoing and incoming workspace have focused windows.

This is only done for click focus mode, since it's not known which
window would be focused for the other modes.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/850

src/core/window-private.h

@@ -704,6 +704,8 @@ void        meta_window_get_session_geometry (MetaWindow  *window,
 
 void        meta_window_update_unfocused_button_grabs (MetaWindow *window);
 
+void        meta_window_appears_focused_changed (MetaWindow *window);
+
 void     meta_window_set_focused_internal (MetaWindow *window,
                                            gboolean    focused);
 

src/core/window.c

@@ -251,6 +251,10 @@ prefs_changed_callback (MetaPreference pref,
       meta_window_recalc_features (window);
       meta_window_queue (window, META_QUEUE_MOVE_RESIZE);
     }
+  else if (pref == META_PREF_FOCUS_MODE)
+    {
+      meta_window_appears_focused_changed (window);
+    }
 }
 
 static void
@@ -4872,6 +4876,9 @@ set_workspace_state (MetaWindow    *window,
         }
     }
 
+  if (!window->constructing)
+    meta_window_appears_focused_changed (window);
+
   /* queue a move_resize since changing workspaces may change
    * the relevant struts
    */
@@ -5171,7 +5178,7 @@ meta_window_change_workspace_by_index (MetaWindow *window,
     meta_window_change_workspace (window, workspace);
 }
 
-static void
+void
 meta_window_appears_focused_changed (MetaWindow *window)
 {
   set_net_wm_state (window);
@@ -7255,7 +7262,17 @@ meta_window_get_frame (MetaWindow *window)
 gboolean
 meta_window_appears_focused (MetaWindow *window)
 {
-  return window->has_focus || (window->attached_focus_window != NULL);
+  MetaWorkspaceManager *workspace_manager;
+  MetaWorkspace *workspace;
+  MetaWindow *default_window = NULL;
+
+  workspace_manager = window->display->workspace_manager;
+  workspace = meta_window_get_workspace (window);
+
+  if (workspace && workspace != workspace_manager->active_workspace)
+    default_window = meta_workspace_get_default_focus_window (workspace);
+
+  return window->has_focus || (window->attached_focus_window != NULL) || (window == default_window);
 }
 
 gboolean

src/core/workspace.c

@@ -365,10 +365,27 @@ meta_workspace_remove (MetaWorkspace *workspace)
    */
 }
 
+static void
+workspace_default_focus_changed (MetaWorkspace *workspace,
+                                 MetaWindow    *not_this_one)
+{
+  GSList *windows, *l;
+
+  windows = meta_display_list_windows (workspace->display, META_LIST_DEFAULT);
+  for (l = windows; l; l = l->next) {
+    MetaWindow *window = META_WINDOW (l->data);
+
+    if (meta_window_located_on_workspace (window, workspace) && window != not_this_one)
+      meta_window_appears_focused_changed (window);
+  }
+}
+
 void
 meta_workspace_add_window (MetaWorkspace *workspace,
                            MetaWindow    *window)
 {
+  MetaWorkspaceManager *manager = workspace->display->workspace_manager;
+
   COGL_TRACE_BEGIN_SCOPED (MetaWorkspaceAddWindow,
                            "Workspace (add window)");
 
@@ -385,6 +402,9 @@ meta_workspace_add_window (MetaWorkspace *workspace,
       meta_workspace_invalidate_work_area (workspace);
     }
 
+  if (workspace != manager->active_workspace)
+    workspace_default_focus_changed (workspace, window);
+
   g_signal_emit (workspace, signals[WINDOW_ADDED], 0, window);
   g_object_notify_by_pspec (G_OBJECT (workspace), obj_props[PROP_N_WINDOWS]);
 }
@@ -393,6 +413,8 @@ void
 meta_workspace_remove_window (MetaWorkspace *workspace,
                               MetaWindow    *window)
 {
+  MetaWorkspaceManager *manager = workspace->display->workspace_manager;
+
   COGL_TRACE_BEGIN_SCOPED (MetaWorkspaceRemoveWindow,
                            "Workspace (remove window)");
 
@@ -409,6 +431,9 @@ meta_workspace_remove_window (MetaWorkspace *workspace,
       meta_workspace_invalidate_work_area (workspace);
     }
 
+  if (workspace != manager->active_workspace)
+    workspace_default_focus_changed (workspace, window);
+
   g_signal_emit (workspace, signals[WINDOW_REMOVED], 0, window);
   g_object_notify (G_OBJECT (workspace), "n-windows");
 }
@@ -657,6 +682,7 @@ meta_workspace_activate_with_focus (MetaWorkspace *workspace,
   if (focus_this)
     {
       meta_window_activate (focus_this, timestamp);
+      workspace_default_focus_changed (workspace, focus_this);
     }
   else if (move_window)
     {