Comment 2 for bug 994142

StacktraceTop:
 g_assertion_message (domain=<optimized out>, file=<optimized out>, line=<optimized out>, func=0x7fbe7cb7c840 "meta_preview_get_icon", message=0x7fbe7f683ec0 "assertion failed: (default_icon)") at /build/buildd/glib2.0-2.28.6/./glib/gtestutils.c:1358
 g_assertion_message_expr (domain=0x7fbe7cb7bd61 "metacity", file=0x7fbe7cb7c7b5 "ui/preview-widget.c", line=450, func=0x7fbe7cb7c840 "meta_preview_get_icon", expr=<optimized out>) at /build/buildd/glib2.0-2.28.6/./glib/gtestutils.c:1369
 meta_preview_get_icon () at ui/preview-widget.c:450
 meta_preview_expose (widget=0x7fbe7f4e5000, event=0x7fbe7f65e5e0) at ui/preview-widget.c:253
 _gtk_marshal_BOOLEAN__BOXED (closure=0x7fbe7f462da0, return_value=0x7fff16f7ac70, n_param_values=<optimized out>, param_values=0x7fbe7f426c40, invocation_hint=<optimized out>, marshal_data=<optimized out>) at /build/buildd/gtk+2.0-2.24.4/gtk/gtkmarshalers.c:86