* In thumbnail view, when you hover over a selected thumb, the hover colour doesn't show because the selected thumb colour takes priority. I think what could usefully done in that instance is for the text area portion to change the colour of the hover. It's importance mostly lies in the way one 'thinks' with the mouse and seeing the hover colour appear is part of that 'thinking', which is a bit thrown by the absence of a hover highlight.
* I think it would be useful in the UI to explain some of the terms. For example under Item: Results List there are a bunch of items labelled 'Hot...' and '... (Highlighted)'; I don't think they will be intuitively obvious to the user what they are for. I'm thinking a little description could appear at the bottom of the dialog describing as a hint whatever you are hovered over, and such hint values could be provided at least for the less intuitive ones. Or alternatively perhaps a link to an online explanation that can be clicked. (In an ideal world perhaps a graphic showing all the UI customisation features exampled and labelled, as often something visual can be more informative than words, though I suspect a visual presentation is the sort of thing the fanbase can do. I did rather like the old XP system where you had a dummy UI schema exhibiting all the possible features and clicked on its parts and changed the colours etc.)
Cheers, David