diff --git a/widget/public/nsIWidget.h b/widget/public/nsIWidget.h
index fa9e72c85fa3..66a1507b43d8 100644
--- a/widget/public/nsIWidget.h
+++ b/widget/public/nsIWidget.h
@@ -57,6 +57,7 @@ typedef nsEventStatus (*PR_CALLBACK EVENT_CALLBACK)(nsGUIEvent *event);
 #define NS_NATIVE_COLORMAP  2
 #define NS_NATIVE_WIDGET    3
 #define NS_NATIVE_DISPLAY   4
+#define NS_NATIVE_REGION		5
 
 // {18032AD5-B265-11d1-AA2A-000000000000}
 #define NS_IWIDGET_IID \