--- a/src/window.h	Fri Dec 07 12:22:34 2007 +0000
+++ b/src/window.h	Fri Dec 07 17:42:15 2007 +0000
@@ -297,7 +297,7 @@
 	void CDECL SetWidgetsDisabledState(bool disab_stat, int widgets, ...);
 	void CDECL SetWidgetsHiddenState(bool hidden_stat, int widgets, ...);
 	void CDECL SetWidgetsLoweredState(bool lowered_stat, int widgets, ...);
-	void InvalidateWidget(byte widget_index);
+	void InvalidateWidget(byte widget_index) const;
 };
 
 struct querystr_d {