Working Nestopia UE GTK+ 64 bit Windows build
I finally got OpenGL to work. Thanks to Google. You basically make a dummy window, and then kill the window after you make the real window. SDL is a pain apparently. The code can be found on Google.
I tested it with a public domain game, it appeared to work.
To open, open a command prompt, cmd, and then drag the exe to it. You might need the -e option too. You can also right click, send to desktop, to crate a shortcut, then right click the shortcut, and click properties, add a space -e at the end.