display: Optionally sort window list

https://bugzilla.gnome.org/show_bug.cgi?id=737581

src/core/display-private.h

@@ -57,6 +57,7 @@ typedef struct MetaEdgeResistanceData MetaEdgeResistanceData;
 typedef enum {
   META_LIST_DEFAULT                   = 0,      /* normal windows */
   META_LIST_INCLUDE_OVERRIDE_REDIRECT = 1 << 0, /* normal and O-R */
+  META_LIST_SORTED                    = 1 << 1, /* sort list by mru */
 } MetaListWindowsFlags;
 
 #define _NET_WM_STATE_REMOVE        0    /* remove/unset property */

src/core/display.c

@@ -150,6 +150,9 @@ static void update_cursor_theme (void);
 static void    prefs_changed_callback    (MetaPreference pref,
                                           void          *data);
 
+static int mru_cmp (gconstpointer a,
+                    gconstpointer b);
+
 static void
 meta_display_get_property(GObject         *object,
                           guint            prop_id,
@@ -1061,6 +1064,9 @@ meta_display_list_windows (MetaDisplay          *display,
       tmp = next;
     }
 
+  if (flags & META_LIST_SORTED)
+    winlist = g_slist_sort (winlist, mru_cmp);
+
   return winlist;
 }