I have 2 21.5" thunderbolt iMacs. I purchased a thunderbolt cable so I can use 1 iMac as a second display for the second one (I know it sounds crazy, but the setup works for me). The target display mode works great via the thunderbolt cable except one problem. In target display mode, the second iMac appears to be on the brightest setting. It seems to me that there is no way for me to change the brightness on the second iMac that I am using as a display. Is anyone else experiencing this problem? Does anyone else know of a solution?