In the main interface window, when there are enough items (Rules, Compliance Checks, etc) to activate the scroll bar, there is a small square area in the upper right where the scroll bar and table headings meet. This area shows up as light blue on my screen, I assume it should be gray.
GlobalUITools::setupTableRendererUI(...)
mess around with the background color setting stuff...
Fiddling with GlobalUITools::setupTableRendererUI() doesn't help. That method deals with the table, but the problem is in the JScrollPane.
I tried setting the background color of the scroll pane and scroll pane viewport in a couple of places without success. I also tried JScrollPane.setCorner() to add a component, but that didn't work, either.