Fix mutter 3.3x crashes (#635)

* Make gala build against Mutter 3.32

* Add schemas override for Mutter 3.3x

* Fix Gala.WorkspaceManager.workspace_removed callback that cause a SIGABRT

* Fix Gala.WorkspaceManager.cleanup method which causes SIGABRT by trying to get non-existing workspaces

* Fix Gala.WorkspaceManager.cleanup method which deletes all workspace instead of keeping at least the last workspace

* Fix Multitasking-View remove_workspace callback which has an incorrect algorithm to remove destroyed workspaces

* Add missing manager.workspace_reordered callback for Mutter 3.34

data/20_elementary.pantheon.wm.gschema.override

@@ -0,0 +1,6 @@
+[org.gnome.mutter:Pantheon]
+dynamic-workspaces = true
+attach-modal-dialogs = false
+button-layout = 'close:maximize'
+edge-tiling = true
+enable-animations = true

data/meson.build

@@ -25,6 +25,7 @@ i18n.merge_file(
 	install_dir: join_paths(data_dir, 'applications')
 )
 install_data(['gala.desktop', 'gala-daemon.desktop', 'gala-wayland.desktop'], install_dir: join_paths(data_dir, 'applications'))
+install_data(files('20_elementary.pantheon.wm.gschema.override'), install_dir: join_paths(data_dir, 'glib-2.0', 'schemas'))
 
 icons_dir = join_paths(get_option('datadir'), 'icons', 'hicolor')
 install_data('icons/32x32/multitasking-view.svg', install_dir: join_paths(icons_dir, '32x32', 'apps'))

src/Background/SystemBackground.vala

@@ -17,7 +17,7 @@
 
 namespace Gala
 {
-#if HAS_MUTTER334
+#if HAS_MUTTER332
 	public class SystemBackground : GLib.Object
 #else
 	public class SystemBackground : Meta.BackgroundActor
@@ -26,7 +26,7 @@ namespace Gala
 		const Clutter.Color DEFAULT_BACKGROUND_COLOR = { 0x2e, 0x34, 0x36, 0xff };
 
 		static Meta.Background? system_background = null;
-#if HAS_MUTTER334
+#if HAS_MUTTER332
     public Meta.BackgroundActor background_actor { get; construct; }
 #endif
 
@@ -35,7 +35,7 @@ namespace Gala
 #if HAS_MUTTER330
 		public SystemBackground (Meta.Display display)
 		{
-#if HAS_MUTTER334
+#if HAS_MUTTER332
 			Object (background_actor: new Meta.BackgroundActor (display, 0));
 #else
 			Object (meta_display: display, monitor: 0);
@@ -57,7 +57,7 @@ namespace Gala
 			}
 
 			if (system_background == null) {
-#if HAS_MUTTER334
+#if HAS_MUTTER332
 				system_background = new Meta.Background (background_actor.meta_display);
 #elif HAS_MUTTER330
 				system_background = new Meta.Background (meta_display);
@@ -68,7 +68,7 @@ namespace Gala
 				system_background.set_file (background_file, GDesktop.BackgroundStyle.WALLPAPER);
 			}
 
-#if HAS_MUTTER334
+#if HAS_MUTTER332
 			background_actor.background = system_background;
 #else
 			background = system_background;

src/Widgets/MultitaskingView.vala

@@ -92,6 +92,9 @@ namespace Gala
 
 			manager.workspace_added.connect (add_workspace);
 			manager.workspace_removed.connect (remove_workspace);
+#if HAS_MUTTER334
+			manager.workspaces_reordered.connect (() => update_positions (false));
+#endif
 			manager.workspace_switched.connect_after ((from, to, direction) => {
 				update_positions (opened);
 			});
@@ -389,29 +392,20 @@ namespace Gala
 			// FIXME is there a better way to get the removed workspace?
 #if HAS_MUTTER330
             unowned Meta.WorkspaceManager manager = display.get_workspace_manager ();
+			List<Workspace> existing_workspaces = null;
+			for (int i = 0; i < manager.get_n_workspaces (); i++) {
+				existing_workspaces.append (manager.get_workspace_by_index (i));
+			}
 #else
 			unowned List<Meta.Workspace> existing_workspaces = screen.get_workspaces ();
 #endif
 
 			foreach (var child in workspaces.get_children ()) {
 				unowned WorkspaceClone clone = (WorkspaceClone) child;
-#if HAS_MUTTER330
-                for (int i = 0; i < manager.get_n_workspaces (); i++) {
-                    if (manager.get_workspace_by_index (i) == clone.workspace) {
-					    workspace = clone;
-					    break;
-                    }
-                }
-
-                if (workspace != null) {
-                    break;
-                }
-#else
 				if (existing_workspaces.index (clone.workspace) < 0) {
 					workspace = clone;
 					break;
 				}
-#endif
 			}
 
 			if (workspace == null)

src/WindowManager.vala

@@ -211,7 +211,7 @@ namespace Gala
 			var system_background = new SystemBackground (screen);
 #endif
 
-#if HAS_MUTTER334
+#if HAS_MUTTER332
 			system_background.background_actor.add_constraint (new Clutter.BindConstraint (stage,
 				Clutter.BindCoordinate.ALL, 0));
 			stage.insert_child_below (system_background.background_actor, null);

src/WorkspaceManager.vala

@@ -132,10 +132,16 @@ namespace Gala
 
 		void workspace_removed (Meta.WorkspaceManager manager, int index)
 		{
+			List<Workspace> existing_workspaces = null;
+			for (int i = 0; i < manager.get_n_workspaces (); i++) {
+				existing_workspaces.append (manager.get_workspace_by_index (i));
+			}
+
 			var it = workspaces_marked_removed.iterator ();
 			while (it.next ()) {
 			    var workspace = it.@get ();
-				if (workspace.index () < 0)
+
+				if (existing_workspaces.index (workspace) < 0)
 					it.remove ();
 			}
 		}
@@ -389,9 +395,13 @@ namespace Gala
 #if HAS_MUTTER330
             unowned Meta.Display display = wm.get_display ();
 			unowned Meta.WorkspaceManager manager = display.get_workspace_manager ();
-			var last_index = manager.get_n_workspaces () - 1;
+			List<Meta.Workspace> workspaces = null;
 			for (int i = 0; i < manager.get_n_workspaces (); i++) {
-			    unowned Meta.Workspace workspace = manager.get_workspace_by_index (i);
+				workspaces.append (manager.get_workspace_by_index (i));
+			}
+
+			foreach (var workspace in workspaces) {
+				var last_index = manager.get_n_workspaces () - 1;
 				if (Utils.get_n_windows (workspace) < 1
 					&& workspace.index () != last_index) {
 					remove_workspace (workspace);