Feature request - Alternative deselect

[awarnock3]

The standard HTML multiple select widget allows select options to be de-selected with Ctrl-click. It would be handy if that also worked for chosen as it would provide a keyboard mechanism for deselecting choices and users are already likely to be familiar with the way to do that. At least, it doesn't seem to work for me.

This would also be handy for those platforms where the chosen-sprite.png sprite does not show on the selected option as an alternative way to deselect choices. I have users reporting this issue on Windows-based browsers, although it does not occur on Linux browsers.

Thanks.