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

I am looking for the same solution. I have written the following code to call ChangeDisplaySettingsEx with PInvoke:

DEVMODE dm = new DEVMODE();
dm.dmSize = (short)Marshal.SizeOf(dm);
dm.dmPelsWidth = 1680;
dm.dmPelsHeight = 1050;
dm.dmBitsPerPel = 32;
dm.dmDisplayFrequency = 60;
dm.dmFields = DevModeFields.DM_BITSPERPEL | DevModeFields.DM_PELSWIDTH | 
              DevModeFields.DM_PELSHEIGHT | DevModeFields.DM_DISPLAYFREQUENCY;
int res = ChangeDisplaySettingsEx(@"\\.\DISPLAY2", ref dm, IntPtr.Zero, CDS_RESET | CDS_UPDATEREGISTRY, IntPtr.Zero);
Console.WriteLine("result = " + res.ToString());

If the monitor is already enabled, this changes the resolution successfully. But if the monitor isn't attached to the desktop already, this won't activate it. So does anyone have a code example that works?