Hi All:

I hope this can help
Try this: (first of all you need the HWND of the window wich will receive the message, in this case ventana)

HWND ventana;
.....


::BringWindowToTop(ventana); //bring ventana to TOP
// simulate Alt + return
keybd_event(VK_MENU,
0,
0,
0);
keybd_event(VK_RETURN,
0,
0,
0);
keybd_event(VK_RETURN,
0,
KEYEVENTF_KEYUP,
0);
keybd_event(VK_MENU,
0,
KEYEVENTF_KEYUP,
0);