Setting minWidth to "auto" works, except that the control ends up being sized such that it's a little too short to prevent the longest options from wrapping. Possibly it's failing to account for the width of the checkbox element itself, or failing to account for the width of the vertical scrollbar.
I'm afraid I don't know the length of the options before hand so I do need the control to set the option width based on the actual text content.
As a secondary request, it'd be great if when you set minWidth to auto if there could be a maxWidth. ie a width beyond which auto is not allowed to go. in other words beyond which it should wrap and/or scroll the option list.