Zimbra Desktop (Free edition)
On the left side of the screen is the list of email accounts to be checked. I have Work, Yahoo, Gmail, and one or two more. Let's call them A, B, C, D, and E from the top down.
When I have account A open, I get A's folders, tags, and zimlets. But accounts B, C, D, and E are flush to the bottom of the screen. In other words, under the Zimlet area there is 5-6 inches of white space. So to look at my D account emails, for example, I have to mouse down past the white space, and then to account D.
Of course, when Account E is open, everything is flush to the top of the screen, and navigation between accounts is much more pleasant and efficient. But as soon as I open account A, for example, the other accounts go back to be flush at the bottom.
What I would like to see: If there are no Zimlets, then close up the white space and move the other accounts up as far as they can be (while still displaying any folders and subfolders for the chosen account).
It's a navigation, user interface thing, but it would certainly be a nice and efficient improvement.