:: SetWindowLong (GetSafeHwnd (), GWL_EXSTYLE, :: GetWindowLongPtr (GetSafeHwnd (), GWL_EXSTYLE) | WS_EX_LAYERED);
dis-> SetLayeredWindowAttributes (0, (255 * 10) / 100, LWA_ALPHA);
This code OnInitDialog dialog in the inside, wherein 10 represents transparency