An application sends the WM_MDIREFRESHMENU message to a multiple document interface (MDI) client window to refresh the Window menu of the MDI frame window.
WM_MDIREFRESHMENU wParam = 0; // not used; must be zero lParam = 0; // not used; must be zero
This message has no parameters.
If the message succeeds, the return value is the handle of the frame window menu.
If the message fails, the return value is NULL.
After sending this message, an application must call the DrawMenuBar function to update the menu bar.