This might be offtopic as I don't use Idea for a long time but what I missed in visual studio was vertical tabs, with productivity power tools I can have them and with regexp, I can even color them but the sorting is very confusing.
As unity dev I click a lot and as I work on a big project I have to use many many classes (500+) and I wrote all of them and during the years it got very messy. Keyboard shortcuts won't help because in unity you need a mouse and if you have to move a hand from mouse and back just to select something and look somewhere then it takes more time then few mouse clicks.
So what I am looking for is tab organization .. I think if there is a possibility to sort them by name and group by a package (directory in unity) it would be better than I have now in VS, where's just an alphabetical order or last save the order.
What I really like on the PPT plugin in VS is that I can have 2 columns of tabs - one for the usual stuff which is very messy and second for the important things I am working on right now but if it's more than one problem (right now I am fixing sound and music and working on one new feature) then it's uncomfortable.
Actually, the idea/rider tabs are already the best but this would help a lot.