[Win 10, x64, Brief]
It would make me very happy if Project/Project Properties/Add Tree supported multi-select so I could add a few trees at once. When dealing with large source trees I often only want to look at a subset of the directories and it is just annoying to have to go via Add Tree multiple times (especially as the tree I'm looking at has selected the thing I selected last time and collapsed its containing directory so I have to expand that again and scroll down to where I was before continuing).
Thanks