I think this probably is a viable wish, since for a checkbox interface I don't think it is proper to have the requirement to press [Ctrl] to check more than one box.
Most definitely. The default behaviour should be to add checked options to previous selections. No one would expect otherwise.
And ideally the first option should be something like
[Reset] to uncheck all options at once.
I can't tell work out what determines the possible filter fields. I can see a couple of my custom tags but not others.
And if it's possible to have virtual tags too that would really open up more possibilities.
Bee excellent to each other...