Code review comment for lp:~intellectronica/lazr-js/choiceedit-position

This branch changes the positioning of the ChoiceEdit control so that the currently selected item is positioned directly under the mouse. This behaviour is more predictable, and we intended to implement it that way originally, but didn't do it because we were hoping that YUI will eventually provide a convenient way to do that. This never happened, and as part of my fix for bug #412925 I just went ahead and implemented it this way (with not much code anyway). The exception to the rule remains that if to position the box correctly will require drawing some of it outside of the viewable area, the position is corrected. I think that's an acceptable compromise, since drawing some of the items out of the screen will be a serious usability problem.