Processing the WM_INITMENUPOPUP Message

Not all clipboard commands are available to the user at any given time. An application should process the WM_INITMENUPOPUP message to enable the menu items for available commands and disable unavailable commands.

Following is the WM_INITMENUPOPUP case for an application named Label.

case WM_INITMENUPOPUP:
    InitMenu((HMENU) wParam);
    break;

The InitMenu function is defined as follows.

void WINAPI InitMenu(HMENU hmenu) 
{ 
    int  cMenuItems = GetMenuItemCount(hmenu); 
    int  nPos; 
    UINT id; 
    UINT fuFlags; 
    PLABELBOX pbox = (hwndSelected == NULL) ? NULL : 
        (PLABELBOX) GetWindowLong(hwndSelected, 0); 
 
    for (nPos = 0; nPos < cMenuItems; nPos++) 
    { 
        id = GetMenuItemID(hmenu, nPos); 
 
        switch (id) 
        { 
            case IDM_CUT: 
            case IDM_COPY: 
            case IDM_DELETE: 
                if (pbox == NULL || !pbox->fSelected) 
                    fuFlags = MF_BYCOMMAND | MF_GRAYED; 
                else if (pbox->fEdit) 
                    fuFlags = (id != IDM_DELETE && pbox->ichSel 
                            == pbox->ichCaret) ? 
                        MF_BYCOMMAND | MF_GRAYED : 
                        MF_BYCOMMAND | MF_ENABLED; 
                else 
                    fuFlags = MF_BYCOMMAND | MF_ENABLED; 
 
                EnableMenuItem(hmenu, id, fuFlags); 
                break; 
 
            case IDM_PASTE: 
                if (pbox != NULL && pbox->fEdit) 
                    EnableMenuItem(hmenu, id, 
                        IsClipboardFormatAvailable(CF_TEXT) ? 
                            MF_BYCOMMAND | MF_ENABLED : 
                            MF_BYCOMMAND | MF_GRAYED 
                    ); 
                else 
                    EnableMenuItem(hmenu, id, 
                        IsClipboardFormatAvailable( 
                                uLabelFormat) ? 
                            MF_BYCOMMAND | MF_ENABLED : 
                            MF_BYCOMMAND | MF_GRAYED 
                    ); 
 
        } 
    } 
}