Appearance tweaks

Some appearance tweaks I made a while ago, now in a separate pull request so they can be more thoroughly discussed.

See some old discussion at https://github.com/textmate/textmate/pull/914

Old:
![screen shot 2013-06-30 at 1 43 43 pm](https://f.cloud.github.com/assets/14237/728220/9f5d2ffa-e1f4-11e2-99e2-c24df4ee7cfb.png)

Cursor tracking rectangles:
![screen shot 2013-06-30 at 1 43 31 pm](https://f.cloud.github.com/assets/14237/728215/7dbaa990-e1f4-11e2-8b0d-610e3b45d36e.png)

New:

![screen shot 2013-06-30 at 7 17 55 pm](https://f.cloud.github.com/assets/14237/728222/a630dc78-e1f4-11e2-9953-d056759526a4.png)
![screen shot 2013-06-30 at 7 17 30 pm](https://f.cloud.github.com/assets/14237/728221/a3e2a4b0-e1f4-11e2-9d56-39be8083e26a.png)

Note: the corner-resize tracking rects are slightly overlapping the buttons, however if you click without dragging, the click **will** go through to the button — i.e., the only thing that is affected is the cursor, which looks like a resize handle when it's over the corner.