(svn r7618) -Feature: Add support for a parent<>child relationship in Window terms. A child

is a window whose parent pointer is non-null. Deleting the parent cascades deleting
 the children as well; children first.

window.h

@@ -335,6 +335,7 @@ struct Window {
 	uint32 desc_flags;
 
 	WindowMessage message;
+	Window *parent;
 	byte custom[WINDOW_CUSTOM_SIZE];
 };