This message informs an application's main windows procedure that a modal dialog box or a menu is entering an idle state. A modal dialog box or menu enters an idle state when no messages are waiting in its queue after it has processed one or more previous messages.
| Parameter | Description |
| wParam | Specifies whether the message is the result of a dialog box or a menu being displayed. It is one of these values: | ||
| Value | Meaning | ||
| MSGF_DIALOGBOX | The system is idle because a dialog box is being displayed. | ||
| MSGF_MENU | The system is idle because a menu is being displayed. | ||
| lParam | Contains in its low-order word the handle of the dialog box (if wParam is MSGF_DIALOGBOX) or of the window containing the displayed menu (if wParam is MSGF_MENU). The high-order word is not used. | ||
The DefWindowProc function returns zero.