[metacity] frames.c: don't try to remove source that does not exist

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 5ae71b165df2fbaae933de41db11726a79aea820
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Tue Jun 3 20:18:46 2014 +0300

    frames.c: don't try to remove source that does not exist

 src/ui/frames.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/ui/frames.c b/src/ui/frames.c
index dcde14e..f0dbb90 100644
--- a/src/ui/frames.c
+++ b/src/ui/frames.c
@@ -1184,6 +1184,8 @@ tip_timeout_func (gpointer data)
 
   show_tip_now (frames);
 
+  frames->tooltip_timeout = 0;
+
   return FALSE;
 }