if(wParam == WM_SYSKEYDOWN && ((KBDLLHOOKSTRUCT*)lParam)->vkCode == VK_LMENU)
        {
            alt_is_down = 1;
        }
        if(wParam = WM_SYSKEYUP && ((KBDLLHOOKSTRUCT*)lParam)->vkCode == VK_LMENU)
        {
            alt_is_down = 0;
        }