The objective: create a slider that, when displaced from the center, increases-decreases the value of another variable at a rate proportional to the displacement.

So, I create a slider that automatically comes back to the center

Slider[Dynamic[var, {(var = #) &, (var = 0.) &}], {-1, 1}]

Now I want a second variable to be dynamically increased/decreased when var!=0.

My ideas are: 1* insert in the previous dynamic, something that does the updating 2* use an animator with it's speed set by var when var!=0. that updates the value

Problems with 1*: how to control the speed of the updating given that I can't know for sure the intervals in which val will be updated, and UpdateIntervals sets an upper bound? Problems with 2*: how to make it work without it showing in the screen?

Any other alternatives are welcome.

Sidenote: ideally I'd like an elegant solution