#2018 follow-on and #2023 - Fixed issues with thumb hover effects.

- cleaned up resize after hover: more efficient, totally browser-compatible (IE7-10, FF, Chrome tested!).
- cleaned up resize on hover: more efficient, fixed bug with neighbors that are bigger but only by a little.
- fixed bugs when moving off item with expanded context menu and then quickly back: oversized hover, flicker.
- cleaned up formatting, removed unneeded code, and added comments.