[mutter] window: Fix crash when mapping sticky window

[Florian Müllner <fmuellner src gnome org>]

commit df90545258a5aa46f3a39f6334c6459b900ce8b2
Author: Florian Müllner <fmuellner gnome org>
Date:   Sat Sep 27 04:11:00 2014 +0200

    window: Fix crash when mapping sticky window
    
    Since the introduction of set_workspace_state(), window->workspace
    will always be NULL when on_all_workspaces is set - passing that
    to a workspace function that does not validate its input will then
    result in a crash.
    Use the get_workspace() function instead, which will always return
    a valid workspace.

 src/core/window.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 5039e30..863027a 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -2095,7 +2095,7 @@ windows_overlap (const MetaWindow *w1, const MetaWindow *w2)
 static gboolean
 window_would_be_covered (const MetaWindow *newbie)
 {
-  MetaWorkspace *workspace = newbie->workspace;
+  MetaWorkspace *workspace = meta_window_get_workspace ((MetaWindow *)newbie);
   GList *tmp, *windows;
 
   windows = meta_workspace_list_windows (workspace);