(You can remove this if this is a thing and I'm just an idiot)
Title
In some of the more complicated machines/builds that use lightwells and containment chalices, especially the evershifting fountain, it could be useful to be able to stop lightwells from interacting with anything on command.

Chalices already support redstone to enable/disable their interactions.

If you have a lightwell outputting a Redstone signal with a comparator, you could use the ability to stop it as a way to hold a specific signal strength with a lightwell.
Wait it took me a sec to understand what I just said. =\
The ability to pause a lightwell's progress manually with a Redstone signal would be useful though

I was talking about specifically about the ability to turn off the output of a lightwell.

Only thing a lightwell outputs to wirelessly is a containment chalice. The intended path for a fountain is to use a chalice, not a lightwell.

I will not include this option