A timed context menu

Raymond Chen

This is sort of in the same spirit as our previous exercise in writing a timed message box, but this is much easier. Here, we use the handy-dandy WM_CANCELMODE message to get us out of menu mode.

MenuTooLateProc(HWND hwnd, UINT uiMsg, UINT idEvent, DWORD dwTime)
  SendMessage(hwnd, WM_CANCELMODE, 0, 0);
TimedTrackPopupMenuEx(HMENU hMenu, UINT uFlags, int x, int y,
    HWND hwnd, LPTPMPARAMS pTpm, DWORD dwTimeout)
    UINT idTimer = SetTimer(NULL, IDT_TOOLATE, dwTimeout, MenuTooLateProc);
    BOOL fResult = TrackPopupMenuEx(hMenu, uFlags, x, y, hwnd, pTpm);
    if (idTimer) KillTimer(NULL, idTimer);
    return fResult;

Before displaying the menu, we set a timer. (And we use a thread timer because we don’t own the hwnd window and therefore don’t know what timer IDs are safe to use.) If the timer fires, we send ourselves a WM_CANCELMODE message to cancel menu mode. This causes the system to act as if the user had dismissed the menu without selecting anything, either by hitting ESC or clicking outside the menu. The call to the TrackPopupMenuEx function returns once the user has selected something (or the timeout has elapsed), at which point we clean up by destroying our timer before returning.