1 files changed, 1 insertions, 1 deletions
diff --git a/xlib/xgc.c b/xlib/xgc.c
index 0cebbc8..c6836bd 100644
--- a/xlib/xgc.c
+++ b/xlib/xgc.c
@@ -465,7 +465,7 @@ 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);