It would be good to be able to scroll within the “Groups” list of the Navigation Bar when pinned. Sometimes there are so many sections, that when it is pinned, this list bleeds off the bottom of the screen, making some sections unselectable.
Yes, it is planned to redesign the section tree. The currently favored solution is to remove the sidebar from the test suite page and move the section tree to the left of the page (with the width resizable, and height scrollable maybe), similar to the Windows Explorer. We will look into it for one of the next version after the next update (2.7).