The Mac OS in 8.5 introduced an option to switch open applications in the finder by choosing "option", "tab". Unfortunately, this is the same command as moving to the next measure in the chord dialog box. There is a way to disable scrolling between applications in the Mac OS. Here's what you do:

1. In the Finder Help menu choose Mac OS Help.
2. Type in the following text: Option Command
3. Click on the hyper text "Switching Between Open Programs"
4. Scroll to the bottom and choose the hyper text "Help me modify the keyboard short cuts".
5. A dialog box to find "Application Switcher" will appear. Point to the Application switcher in the System folder/Extensions folder or System folder/Extensions Disabled folder.
6. You'll then get a dialog box that asks you if you would like to use keyboard short cut to switch applications. Choose "no".

Now you should be able to move to the next measure without switching applications or going to the finder.