Hello,
When you created your window (using CreateWindow or CreateWindowEx function), you probably put the WS_OVERLAPPEDWINDOW style. Just have to replace this by other styles, look in MSDN for more information. If you want the same thing of overlappedwindow without sizing, here the styles you will have to put. WS_OVERLAPPED|WS_CAPTION|WS_SYSMENU|WS_MINIMIZEBOX|WS_MAXIMIZEBOX .

Hope that helped you