A common problem my students and I have been having is with the item tabs. One option I'd love to see is being able to 'scroll' through the items in the Overview window and having them appear tab area. Right now you need to click on each item to see it and it opens a bunch of tabs, which quickly become too numerous and push the window to the right.
Perhaps you could always have a "Overview" button to the left of the tabs. When this button is selected/active, whatever item is highlighted in the overview panel (either through clicking or scrolling), then appears as a special "tab" window.
Relatedly, it would also be very helpful if when open a lot of tabs, instead of pushing the window to the right, the tabs automatically stacked as multiple rows, instead of a really long single row.