Thumbnail mode: Fix segfault when opening a deleted/renamed file

ChangeLog

+git HEAD
+
+    * Fix segfault in Thumbnail mode when trying to open a no longer
+      existing image (e.g. when the file was renamed by a previous action)
+
 Sat Jun  5 21:35:25 CEST 2010  Daniel Friesel <derf@chaosdorf.de
 
 * Release v1.6.1

src/events.c

@@ -251,7 +251,8 @@ static void feh_event_handle_ButtonRelease(XEvent * ev)
 						thumbwin = winwidget_create_from_file(
 								gib_list_add_front(NULL, thumbfile),
 								s, WIN_TYPE_THUMBNAIL_VIEWER);
-						winwidget_show(thumbwin);
+						if (thumbwin)
+							winwidget_show(thumbwin);
 					} else if (FEH_FILE(thumbwin->file->data) != thumbfile) {
 						free(thumbwin->file);
 						thumbwin->file = gib_list_add_front(NULL, thumbfile);