Adding/removing decision behavior can be un-intuitive

[hudson-newey]

When sub-selecting two tiles, one with decision “foo”, and one without decision “foo”, clicking the “foo” decision will toggle the decision state on each tile.

Users have expressed that they'd expect the decision to be added to all sub-selected tiles that did not have the decision, then if all tiles have the decision, for the decision to be removed from all selected tiles.

[atruskie]

So, with a sub-selection that has a mixed state of the current decision, we apply a uniform decision on activation.

I.e. 1 not koala, 1 koala, koala positive applied, both end up with koala positive.

Link to removing positive only classification: #135. If we solve that, then this is a non-issue.