This is basically a usability enhancement for a specific tool (the "fuzzy
select" tool).

The way I work with "fuzzy select" now is like this:
- I click somewhere on an image
- I see that it hasn't selected enough, or that it selected too much.
- I change the treshold
- I do "shift-ctrl-A" to select none
- I try to find the same spot I clicked previously, and click on it again
- I repeat the procedure until I'm happy with the selection

Of course this all happens rather quickly.

However two problems with this:
1) There's a lot of steps to do, and I basically always have to pick an
approximative treshold, which might often be wrong.
2) Since every time I click on a different pixel, I always pick a treshold
(relative to the previous treshold) based on what might be a different base colour.

So it would be nice if:
- I click somewhere on an image
- I see that it hasn't selected enough, or that it selected too much.
- I change the treshold, and while I change I see the selection change, so when
I release the slider, it's almost exactly where I want it.

Less steps, direct feedback of what you're doing, no mistakes. 

This kind of direct feedback might be interesting for other tools as well; If
the architecture makes it easy, it might be worth considering it for other tools
too.


Thank you for considering this enhancement, and for your great work on Gimp.
It's very much appreciated.