placed in dead area in the corner where the horizontal/vertical scrollbars are:

If I try to click the CheckBox, nothing happens. I've tried setting it to always
be on top (SetWindowPos API) and it doesn't help, and neither does setting
the StringGadget to not-on-top. If I press TAB to the CheckBox to give it the
focus, and then hit Space, I can set/unset it, but obviously I'd like it to also
work with mouse clicks. Any ideas?