The CDN_INITDONE notification message is sent by an Explorer-style Open or Save As common dialog box when the system has finished arranging the controls in the dialog box. The system moves the standard controls to make room for the controls of the child dialog box. Your OFNHookProc hook procedure receives this message in the form of a WM_NOTIFY message.
CDN_INITDONE lpon = (LPOFNOTIFY) lParam;
The OFNOTIFY structure contains an NMHDR structure whose code member indicates the CDN_INITDONE notification code.
The return value is ignored.
The system sends this notification only if the dialog box was created using the OFN_EXPLORER value.
GetOpenFileName, GetSaveFileName, NMHDR, OFNHookProc, OFNOTIFY, OPENFILENAME, WM_NOTIFY