Constant characters sometimes show selection on there own.

[ramorrismorris]

With the deployment on etc-dev, select any value for state of first character. Some constant characters (at the bottom, entropy zero) are showing check mark, some not. Aside from whether constant characters should be offered at all (issue #71), I can't make any sense of this.

[shizhuoyu]

When one of the states of a character is selected, the state of this selected character becomes unique of the remaining taxa (this character become constant), so the entropy become zero. (Case 1: showing check mark)
But this process will shrink the pool of remaining taxa, which may result in some other characters become constant even though they have not been selected before (Case 2: not showing check mark)
I was remembering Hong mentioned this CFG work should look like a "bestbuy online shopping filter", user can select/unselect characters, so Case 1 is used to apply this here, and Case 2 dynamically happens based on the select/unselect at each round.