show background when nautilus isn't drawing the desktop.

If window with type Meta.WindowType.DESKTOP doesn't exist, then draw
background.
https://bugzilla.gnome.org/show_bug.cgi?id=591912

js/ui/main.js

@@ -46,6 +46,10 @@ let modalActorFocusStack = [];
 let _errorLogStack = [];
 let _startDate;
 
+let background = null;
+let _windowAddedSignalId = null;
+let _windowRemovedSignalId = null;
+
 function start() {
     // Add a binding for "global" in the global JS namespace; (gjs
     // keeps the web browser convention of having that namespace be
@@ -134,7 +138,12 @@ function start() {
         }
     });
 
-    _relayout();
+    background = global.create_root_pixmap_actor();
+    global.screen.connect('workspace-switched', _onWorkspaceSwitched);
+    global.stage.add_actor(background);
+    background.lower_bottom();
+    _onWorkspaceSwitched(global.screen, -1);
+
     global.connect('screen-size-changed', _relayout);
 
     ExtensionSystem.init();
@@ -195,12 +204,53 @@ function _getAndClearErrorStack() {
     return errors;
 }
 
+function showBackground() {
+    background.show();
+}
+
+function hideBackground() {
+    background.hide();
+}
+
+function _onWorkspaceSwitched(screen, from) {
+    let workspace = screen.get_active_workspace();
+
+    if (from != -1) {
+        let old_workspace = screen.get_workspace_by_index(from);
+
+        if (_windowAddedSignalId !== null)
+            old_workspace.disconnect(_windowAddedSignalId);
+        if (background.windowRemovedSignalId !== null)
+            old_workspace.disconnect(_windowRemovedSignalId);
+    }
+
+    _windowAddedSignalId = workspace.connect('window-added', function(win) {
+        if (win.window_type == Meta.WindowType.DESKTOP)
+            hideBackground();
+    });
+    _windowRemovedSignalId = workspace.connect('window-removed', function(win) {
+        if (win.window_type == Meta.WindowType.DESKTOP)
+            showBackground();
+    });
+
+    function _isDesktop(win) {
+        return win.window_type == Meta.WindowType.DESKTOP;
+    }
+
+    if (workspace.list_windows().some(_isDesktop))
+        hideBackground();
+    else
+        showBackground();
+}
+
 function _relayout() {
     let primary = global.get_primary_monitor();
     panel.actor.set_position(primary.x, primary.y);
     panel.actor.set_size(primary.width, Panel.PANEL_HEIGHT);
     overview.relayout();
 
+    background.set_size(global.screen_width, global.screen_height);
+
     // To avoid updating the position and size of the workspaces
     // in the overview, we just hide the overview. The positions
     // will be updated when it is next shown. We do the same for

js/ui/workspace.js

@@ -287,10 +287,10 @@ DesktopClone.prototype = {
             this.actor = new Clutter.Clone({ source: window.get_texture(),
                                              reactive: true });
         } else {
-            this.actor = new Clutter.Rectangle({ color: global.stage.color,
+            this.actor = new Clutter.Clone({ source: Main.background.source,
-                                                 reactive: true,
+                                             reactive: true,
-                                                 width: global.screen_width,
+                                             width: global.screen_width,
-                                                 height: global.screen_height });
+                                             height: global.screen_height });
         }
 
         this.actor.connect('button-release-event',

src/shell-global.c

@@ -28,6 +28,7 @@
 #define SHELL_DBUS_SERVICE "org.gnome.Shell"
 
 static void grab_notify (GtkWidget *widget, gboolean is_grab, gpointer user_data);
+static void update_root_window_pixmap (ShellGlobal *global);
 
 struct _ShellGlobal {
   GObject parent;
@@ -481,11 +482,7 @@ global_stage_notify_width (GObject    *gobject,
                            gpointer    data)
 {
   ShellGlobal *global = SHELL_GLOBAL (data);
-  ClutterActor *stage = CLUTTER_ACTOR (gobject);
 
-  if (global->root_pixmap)
-    clutter_actor_set_width (CLUTTER_ACTOR (global->root_pixmap),
-                             clutter_actor_get_width (stage));
   g_object_notify (G_OBJECT (global), "screen-width");
 
   meta_later_add (META_LATER_BEFORE_REDRAW,
@@ -500,11 +497,7 @@ global_stage_notify_height (GObject    *gobject,
                             gpointer    data)
 {
   ShellGlobal *global = SHELL_GLOBAL (data);
-  ClutterActor *stage = CLUTTER_ACTOR (gobject);
 
-  if (global->root_pixmap)
-    clutter_actor_set_height (CLUTTER_ACTOR (global->root_pixmap),
-                              clutter_actor_get_height (stage));
   g_object_notify (G_OBJECT (global), "screen-height");
 
   meta_later_add (META_LATER_BEFORE_REDRAW,
@@ -1042,6 +1035,9 @@ shell_global_create_root_pixmap_actor (ShellGlobal *global)
     {
       global->root_pixmap = clutter_glx_texture_pixmap_new ();
 
+      clutter_texture_set_repeat (CLUTTER_TEXTURE (global->root_pixmap),
+                                  TRUE, TRUE);
+
       /* The low and medium quality filters give nearest-neighbor resizing. */
       clutter_texture_set_filter_quality (CLUTTER_TEXTURE (global->root_pixmap),
                                           CLUTTER_TEXTURE_QUALITY_HIGH);