Implementing getMouseDragSensitivity in Sliders

Hello,

I was in the need to know the current sensitivity of a linear dragging slider, and found out that the Slider has the setMouseDragSensitivity method but no getMouseDragSensitivity. I think it’s a good idea to implement that for completeness, I don’t see how it could be of any harm.

Absolutely, I’ll add that. Thanks!