Parent notifications

[Dimitrie O. Paun]

I've found this in control/edit.c

HWND hwndParent;               /* Handle of parent for sending EN_* messages.
                                          Even if parent will change, EN_* messages
                                          should be sent to the first parent. */

Is this true for all controls? Common controls as well?
Can someone with a Windows box experiment, and see what's going on?

TIA,
Dimi.