How do I enable a second monitor in C#?

Question

Is it possible to enable a second monitor programatically and extend the Windows Desktop onto it in C#? It needs to do the equivalent of turning on the checkbox in the image

Answer 1

To enable a monitor, set its position to something other than 0,0, like as shown:

POINTL enabledPosition = new POINTL();
enabledPosition.x = -1280;
enabledPosition.y = 0;

dm.dmPosition = enabledPosition;
dm.dmFields = DM.Position;
res = ChangeDisplaySettingsEx(d.DeviceName, ref dm, IntPtr.Zero, (uint) DeviceFlags.CDS_UPDATEREGISTRY, IntPtr.Zero);