Selections should allow cumulation rather than replacement

From an e-mail from Dennis C.

so that this selection method could be combined with Select Cells/Points On/Through with the “Add Selection” to finetune a selection. Alternately should “Select Block” be smarter and only select Block Cells if the current Selection is Cells, or only select Block Points if the current Selection is Points (and add them to the existing selection instead of replacing it?

Reply from Utkarsh:

Ah! That's cool and not easily supportable the way things are currently. But Berk and I were chatting and we have an approach to support combining multiple selections add/remove/etc. nicely. Now just convince Alan to make it a priority and I'd love to have it sorted out for the SC release ;).