Possible, but useless? How about putting them in the shortcut list (the block to the right of the quickbar, heck if I knew the "correct" official term).
I mean, I made a second productivity module requester and then found out the configuration (which tier to request) is shared among all productivity module requesters.
And now, how do I get rid of a requester? It doesn't have a delete button like blueprints do…
