Pin Folders in the Folder Tree
I thought it would be a useful feature to have the option to Pin Folders in the Folder Tree so that they stay expanded, while still having the "Collapse non-selected branches" option enabled. I often have to re-expand Favorites to be able to navigate to them, but don't want to get stuck with an enormous tree in a session by disabling that option.
Freeze Folders in the Folder Tree
Being able to keep selected folders visible at the top of the folder tree would be a useful option.
Set Specific Folders to not Expand in the Folder Tree
For folders with many subfolders it can make using the Folder Tree a pain due to all the scrolling to be able to navigate to a different folder or collapse the parent folder. It would also be useful to have the option to hide hide all child branches of a folder except the ones that are open in a tab.