1 files changed, 1 insertions, 1 deletions
diff --git a/xlib/xgc.c b/xlib/xgc.c
index 6c5e31c..fcc2798 100644
--- a/xlib/xgc.c
+++ b/xlib/xgc.c
@@ -436,7 +436,7 @@ TkSetRegion(
     TkRegion r)
 {
     if (r == None) {
-	FreeClipMask(gc);
+	Tcl_Panic("must not pass None to TkSetRegion for compatibility with X11; use XSetClipMask instead");
     } else {
 	TkpClipMask *clip_mask = AllocClipMask(gc);