This procedure is the same as any other window procedure, except that it can receive predefined window messages specific to dialog box windows.
Note: It does not receive the WM_CREATE message, but the same information is carried by the WM_INITDLG message, that is generated during the creation of a dialog-box window.
hwnd is always the window handle of the dialog-box window.
The dialog procedure typically processes only some of the messages passed to it. Any messages that it does not process must be passed to WinDefFileDlgProc if the dialog box is the standard file selection dialog, WinDefFontDlgProc if the dialog box is the standard font selection dialog box, or for all other dialog boxes, WinDefDlgProc (not WinDefWindowProc), because these perform the standard dialog-box processing for those messages.