Some additional seamless skin polish items

### Fixed-width dropdowns

The dropdowns should be just as wide as their header, otherwise it's easy to accidentally un-hover.

### Shrink the height

When content is removed, shrink the height (stopping when you hit the height of the original textarea).

### IE call initIframe twice

This results in some initialization being duplicated.

### Add a delayed height recalculation

If the editor contains images on initialization that don't have height defined,
the initial editor height will be off if they haven't loaded by calculation time.
A quick, IE7-compatible fix is to just set a one time timer to recalculate a couple of seconds later.
Not a perfect solution, but good enough.

### IE8 always grows

Both IE7 and IE8 run two resize loops every key press,
but IE8 always grows by at least 10px.,
even if you're hitting backspace.
Something is up with the desiredHeight calculation :(

### Pasting should update height

If a user pastes in content, we probably need to grow the editor. Trigger a height check on that event.