Documentation pane on openEditor is unresponsive on IE8

[dyoo]

Reported by "Lee" Leland Nickleson: "When I opened the documentation window, it was very narrow and wouldn’t expand when I was using IE 8. It worked OK in Firefox by dragging the right side open."

The Documentation pane does move, but it is very laggy under IE8. The drag button on the bottom right is also very unresponsive under IE8. It may be that we need to switch over to opaque dragging when we detect IE8, because it's just too sluggish otherwise.

[schanzer]

IE8 will be unsupported soon - I'd say punt on this.