Excellent suggestions Augusto. Thanks a lot. The first 4 is actually already on our todo list. 🙂
The fifth is not something I have thought of before. Seems very usable though. As you probably already know, you can move the divider to show more of the x-sheet, also you can set your thumbnails to a smaller size to make room for more, and finally, you can detach the x-sheet to have it in a separate window and make it as big as you like – you can even use a second monitor and have the x-sheet full screen there.
Let me know if any of this helps your situation with point 5 – I appreciate it is not exactly what you asked for. 😉