The folders are a problem, and that is when you drag the parent or a child track outside of its folder space. I think Cockos are on top of that situation. Several solutions are possible. It'll depend what the default should be, and what should be done with modifiers. When moving outside the folder area with your dragged/selected track(s) should the entire folder range be moved right along, as if you're automatically selecting the parent folder and all its children tracks, or, should the default be to let the user just drag stuff outside but have Reaper remind the user of the implications with a visual hint ? This could take the form of a simple red(instead of blue=moving with no possible problems) surrounding the entire folder area.