Update _NET_CURRENT_DESKTOP on workspace removal

When we delete a workspace before the active workspace, we need
to upate the _NET_CURRENT_DESKTOP since the active workspace index
changes. To do this workspace.c:set_active_space_hint() is moved
to screen.c:meta_screen_set_active_workspace_hint() so that it
can be shared.

https://bugzilla.gnome.org/show_bug.cgi?id=640581

src/core/screen-private.h

@@ -255,4 +255,6 @@ void     meta_screen_workspace_switched (MetaScreen         *screen,
                                          int                 to,
                                          MetaMotionDirection direction);
 
+void meta_screen_set_active_workspace_hint (MetaScreen *screen);
+
 #endif

src/core/screen.c

@@ -1283,6 +1283,7 @@ meta_screen_remove_workspace (MetaScreen *screen, MetaWorkspace *workspace,
   MetaWorkspace *neighbour = NULL;
   GList         *next = NULL;
   int            index;
+  gboolean       active_index_changed;
   int            new_num;
 
   l = screen->workspaces;
@@ -1321,6 +1322,7 @@ meta_screen_remove_workspace (MetaScreen *screen, MetaWorkspace *workspace,
 
   /* To emit the signal after removing the workspace */
   index = meta_workspace_index (workspace);
+  active_index_changed = index < meta_screen_get_active_workspace_index (screen);
 
   /* This also removes the workspace from the screens list */
   meta_workspace_remove (workspace);
@@ -1330,6 +1332,11 @@ meta_screen_remove_workspace (MetaScreen *screen, MetaWorkspace *workspace,
   set_number_of_spaces_hint (screen, new_num);
   meta_prefs_set_num_workspaces (new_num);
 
+  /* If deleting a workspace before the current workspace, the active
+   * workspace index changes, so we need to update that hint */
+  if (active_index_changed)
+      meta_screen_set_active_workspace_hint (workspace->screen);
+
   l = next;
   while (l)
     {
@@ -3345,3 +3352,29 @@ meta_screen_workspace_switched (MetaScreen         *screen,
                  from, to, direction);
 }
 
+void
+meta_screen_set_active_workspace_hint (MetaScreen *screen)
+{
+  unsigned long data[1];
+
+  /* this is because we destroy the spaces in order,
+   * so we always end up setting a current desktop of
+   * 0 when closing a screen, so lose the current desktop
+   * on restart. By doing this we keep the current
+   * desktop on restart.
+   */
+  if (screen->closing > 0)
+    return;
+  
+  data[0] = meta_workspace_index (screen->active_workspace);
+
+  meta_verbose ("Setting _NET_CURRENT_DESKTOP to %lu\n", data[0]);
+  
+  meta_error_trap_push (screen->display);
+  XChangeProperty (screen->display->xdisplay, screen->xroot,
+                   screen->display->atom__NET_CURRENT_DESKTOP,
+                   XA_CARDINAL,
+                   32, PropModeReplace, (guchar*) data, 1);
+  meta_error_trap_pop (screen->display);
+}
+

src/core/workspace.c

@@ -24,6 +24,7 @@
  */
 
 #include <config.h>
+#include "screen-private.h"
 #include "workspace.h"
 #include "workspace-private.h"
 #include "boxes-private.h"
@@ -45,7 +46,6 @@ enum {
 };
 
 void meta_workspace_queue_calc_showing   (MetaWorkspace *workspace);
-static void set_active_space_hint        (MetaScreen *screen);
 static void focus_ancestor_or_mru_window (MetaWorkspace *workspace,
                                           MetaWindow    *not_this_one,
                                           guint32        timestamp);
@@ -557,7 +557,7 @@ meta_workspace_activate_with_focus (MetaWorkspace *workspace,
 
   workspace->screen->active_workspace = workspace;
 
-  set_active_space_hint (workspace->screen);
+  meta_screen_set_active_workspace_hint (workspace->screen);
 
   /* If the "show desktop" mode is active for either the old workspace
    * or the new one *but not both*, then update the
@@ -752,32 +752,6 @@ meta_workspace_list_windows (MetaWorkspace *workspace)
   return workspace_windows;
 }
 
-static void
-set_active_space_hint (MetaScreen *screen)
-{
-  unsigned long data[1];
-
-  /* this is because we destroy the spaces in order,
-   * so we always end up setting a current desktop of
-   * 0 when closing a screen, so lose the current desktop
-   * on restart. By doing this we keep the current
-   * desktop on restart.
-   */
-  if (screen->closing > 0)
-    return;
-  
-  data[0] = meta_workspace_index (screen->active_workspace);
-
-  meta_verbose ("Setting _NET_CURRENT_DESKTOP to %lu\n", data[0]);
-  
-  meta_error_trap_push (screen->display);
-  XChangeProperty (screen->display->xdisplay, screen->xroot,
-                   screen->display->atom__NET_CURRENT_DESKTOP,
-                   XA_CARDINAL,
-                   32, PropModeReplace, (guchar*) data, 1);
-  meta_error_trap_pop (screen->display);
-}
-
 void
 meta_workspace_invalidate_work_area (MetaWorkspace *workspace)
 {