I recently went from Snow Leopard to Mountain Lion. Previously, my monitor connected via DisplayLink correctly set the maximum resolution of my display to 1920x1080. It now incorrectly sets the max resolution to 1280x1024. The highest resolution I can set the monitor to without distortion, due to the wrong aspect ratio, is 1280 x 800.
My monitor is an Acer S231HL
http://support.acer.com/acerpanam/MO...231HLsp2.shtml
As a fellow software developer, I urge you to create a tool for advanced users that would allow a person to input the maximum resolution and refresh rate manually. I know this is probably easier said then done.