--- backend_gtk.py.orig	2011-09-06 14:24:37.292309600 +0200
+++ backend_gtk.py	2011-09-06 14:29:02.601021800 +0200
@@ -496,7 +496,7 @@
 
         self.window = gtk.Window()
         self.window.set_title("Figure %d" % num)
-        if (window_icon):
+        if (window_icon) and gtk.window_get_default_icon_list() is None:
             try:
                 self.window.set_icon_from_file(window_icon)
             except: