Tab toggles screen 50. If you don't want TAB to do anything, don't use screen 50. If you want to toggle other screens, you''ll need to do it with VB code. It won't work exactly the same, though. You'd really just be changing screens, and then going back to a previous one. Screen 50 is the only one that'll flyout.
To add screens, just choose the # from a drop down list. There are 99 available.