When trying to change program setting, more than one selection hi lighted. See screen shot.
Lewis - Have you set the program scaling (in Program Settings) to something other than 100%? I have noticed a number of similar graphical glitches when I tried 80% on my Macbook which I've never had at 100%.
Stephen, I changed program scaling to 110%. However id did find that if I place my pointer over the tools selection and arrow down, I could get tools to work properly. This allowed me to change all setting back to default setting.
Program Scaling has a number of known issues caused by bugs in OS X and Cocoa, and the feature will likely be removed in a future release.