What's the best way of concealing the join/hinge lines?

I'd prefer to grout the joins to keep them hidden, but will grout just
fall out with a bit of movement? With hinges I'd be a bit concerned
that the panel wouldn't be totally secure and the grout around the
edge of the panel would come loose.

Also, is there some way of stopping the grout sticking to one side of
the grout line?

Or is it best to seal the panel with sealant and put up with having to
cut it to open the panel?