[mutter] x11-display: Split out restoring of active workspace

[Florian Müllner <fmuellner src gnome org>]

commit 7abceb434dedaa2b1f2c7fc20aa2907cd3a041f6
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Mar 1 12:03:46 2019 +0100

    x11-display: Split out restoring of active workspace
    
    Splitting out the X11 display initialization from display_open() broke
    restoring the previously active workspace in two ways:
    
     - when dynamic workspaces are used, the old workspaces haven't
       been restored yet, so we stay on the first workspace
    
     - when static workspaces are used, the code tries to access
       the compositor that hasn't been initialized yet, resulting
       in a segfault
    
    Fix both those issues by splitting out restoring of the active workspace.
    
    https://gitlab.gnome.org/GNOME/mutter/issues/479

 src/core/display.c                 |  5 ++-
 src/x11/meta-x11-display-private.h |  2 ++
 src/x11/meta-x11-display.c         | 62 +++++++++++++++++++++++---------------
 3 files changed, 43 insertions(+), 26 deletions(-)
---
diff --git a/src/core/display.c b/src/core/display.c
index eb976e055..e1477d3cd 100644
--- a/src/core/display.c
+++ b/src/core/display.c
@@ -751,7 +751,10 @@ meta_display_open (void)
   enable_compositor (display);
 
   if (display->x11_display)
-    meta_x11_display_create_guard_window (display->x11_display);
+    {
+      meta_x11_display_restore_active_workspace (display->x11_display);
+      meta_x11_display_create_guard_window (display->x11_display);
+    }
 
   /* Set up touch support */
   display->gesture_tracker = meta_gesture_tracker_new ();
diff --git a/src/x11/meta-x11-display-private.h b/src/x11/meta-x11-display-private.h
index 7497f7512..b10411888 100644
--- a/src/x11/meta-x11-display-private.h
+++ b/src/x11/meta-x11-display-private.h
@@ -156,6 +156,8 @@ struct _MetaX11Display
 
 MetaX11Display *meta_x11_display_new (MetaDisplay *display, GError **error);
 
+void meta_x11_display_restore_active_workspace (MetaX11Display *x11_display);
+
 Window meta_x11_display_create_offscreen_window (MetaX11Display *x11_display,
                                                  Window          parent,
                                                  long            valuemask);
diff --git a/src/x11/meta-x11-display.c b/src/x11/meta-x11-display.c
index 47fb47f83..8ce12b994 100644
--- a/src/x11/meta-x11-display.c
+++ b/src/x11/meta-x11-display.c
@@ -1068,8 +1068,6 @@ meta_x11_display_new (MetaDisplay *display, GError **error)
   Atom wm_sn_atom;
   char buf[128];
   guint32 timestamp;
-  MetaWorkspace *current_workspace;
-  uint32_t current_workspace_index = 0;
   Atom atom_restart_helper;
   Window restart_helper_window = None;
   GdkDisplay *gdk_display;
@@ -1275,27 +1273,6 @@ meta_x11_display_new (MetaDisplay *display, GError **error)
 
   meta_x11_display_update_workspace_layout (x11_display);
 
-  /* Get current workspace */
-  if (meta_prop_get_cardinal (x11_display,
-                              x11_display->xroot,
-                              x11_display->atom__NET_CURRENT_DESKTOP,
-                              &current_workspace_index))
-    {
-      meta_verbose ("Read existing _NET_CURRENT_DESKTOP = %d\n",
-                    (int) current_workspace_index);
-
-      /* Switch to the _NET_CURRENT_DESKTOP workspace */
-      current_workspace = meta_workspace_manager_get_workspace_by_index (display->workspace_manager,
-                                                                         current_workspace_index);
-
-      if (current_workspace != NULL)
-        meta_workspace_activate (current_workspace, timestamp);
-    }
-  else
-    {
-      meta_verbose ("No _NET_CURRENT_DESKTOP present\n");
-    }
-
   if (meta_prefs_get_dynamic_workspaces ())
     {
       int num = 0;
@@ -1315,8 +1292,6 @@ meta_x11_display_new (MetaDisplay *display, GError **error)
           meta_workspace_manager_update_num_workspaces (display->workspace_manager, timestamp, num);
     }
 
-  set_active_workspace_hint (display->workspace_manager, x11_display);
-
   g_signal_connect_object (display->workspace_manager, "active-workspace-changed",
                            G_CALLBACK (set_active_workspace_hint),
                            x11_display, 0);
@@ -1356,6 +1331,43 @@ meta_x11_display_new (MetaDisplay *display, GError **error)
   return x11_display;
 }
 
+void
+meta_x11_display_restore_active_workspace (MetaX11Display *x11_display)
+{
+  MetaDisplay *display;
+  MetaWorkspace *current_workspace;
+  uint32_t current_workspace_index = 0;
+  guint32 timestamp;
+
+  g_return_if_fail (META_IS_X11_DISPLAY (x11_display));
+
+  display = x11_display->display;
+  timestamp = x11_display->timestamp;
+
+  /* Get current workspace */
+  if (meta_prop_get_cardinal (x11_display,
+                              x11_display->xroot,
+                              x11_display->atom__NET_CURRENT_DESKTOP,
+                              &current_workspace_index))
+    {
+      meta_verbose ("Read existing _NET_CURRENT_DESKTOP = %d\n",
+                    (int) current_workspace_index);
+
+      /* Switch to the _NET_CURRENT_DESKTOP workspace */
+      current_workspace = meta_workspace_manager_get_workspace_by_index (display->workspace_manager,
+                                                                         current_workspace_index);
+
+      if (current_workspace != NULL)
+        meta_workspace_activate (current_workspace, timestamp);
+    }
+  else
+    {
+      meta_verbose ("No _NET_CURRENT_DESKTOP present\n");
+    }
+
+  set_active_workspace_hint (display->workspace_manager, x11_display);
+}
+
 int
 meta_x11_display_get_screen_number (MetaX11Display *x11_display)
 {