It would be beneficial to allow for stack bounties to support tags, so that you only have to get a certain kind of block. There exists a problem, though:

Lets say a bounty asks for 5 blue dye AND 7 of any generic tagged dye. You have 10 dye (6 blue, 4 red). Therefore, you meet both conditions but the bounty still wouldn't be possible. Therefore, when picking stacks, you'd have to start with named stacks and "reserve" them so that they don't get picked up when checking for tag stacks.

Okay, this has been implemented fully as of 6edfc70. Currently, in the scenario described above the tooltip would read as so:

Requires:
(5/5) Blue Dye
(5/7) Any Dye