Sometimes you click the select/unselect box and nothing happens – i.e. it
doesn't select or unselect.
I suspect it is the bizarre and not strictly correct use of the "mousePressed"
flag in Renderers.java
note: this is a pre-existing bug I discovered while researching #182 – it was
NOT caused by the fix for 182.
Somebody else (Nolan, Steve, RR) – please verify the bug...