title: Crash when top most window in stack is null

#0  0x00007a3b382a5751 in is_window_on_active_workspace_and_no_other_maximized_windows_above (window=0x5856402108e0) at wcktitle-title.c:65
65	   while (top_window->data != window && top_window != bottom_window) {
[Current thread is 1 (Thread 0x7a3b35e535c0 (LWP 890312))]
gdb$ display top_window
1: top_window = 0x0

Fixed by the following patch

diff --git a/panel-plugin/title/wcktitle-title.c b/panel-plugin/title/wcktitle-title.c
index 36179d1..172d881 100644
--- a/panel-plugin/title/wcktitle-title.c
+++ b/panel-plugin/title/wcktitle-title.c
@@ -62,7 +62,7 @@ static gboolean is_window_on_active_workspace_and_no_other_maximized_windows_abo
     windows = wnck_screen_get_windows_stacked(screen);
     top_window = g_list_last(windows);
     bottom_window = g_list_first(windows);
-    while (top_window->data != window && top_window != bottom_window) {
+    while (top_window != NULL && top_window->data != window && top_window != bottom_window) {
         if (wnck_window_is_maximized((Wn\kWindow *)top_window->data)) {
             return FALSE;
         }

probably related #19 (closed)