Does anybody know if there is a way to run the program so it works full screen on a 20 inch Cinema Display? There doesn't seem to be a way to get that to work.
You can change x-plane's size in "Rendering Options", under the menu titled "Settings." On my 17 inch formac gallery, x-plane won't run in fullscreen. Be careful when changing x-plane's resolution: I used a non-standard size once and it rendered the game unplayable. I had to then reinstall it. I run it at 1080 x 1024 (pixels). I'm not sure about the 20 inch cinema display, but it should appear pretty big, depending on your graphics card. This information is taken from x-plane 730. http://www.xplanehelp.com/ is also a good site for x-plane questions.
I run X-plane at 1680x1024 with no problems at all Just set it in the Rendering Options and you shall have no problems at all. Of course the cockpit view will be in the middle of the screen with scenery on the sides but if you will be able to live with that.