[2.0pb7] remove extra space between UI elements?

Some spots in a few views look like they have some unnecessary space between edges of UI elements. For example:

Three Panes.png
It’s most obvious around the top-right pane in Three Panes view. Not sure that’s intentional but I think it would look cleaner without it. Thanks.

That’s of course not final yet, polishing several parts of the UI is one of the last steps.