Help with LinearBarVertical drag sensitivity

I'm trying to create a LinearBarVertical slider with mouse drag movement similar to a RotaryVerticalDrag. I like how you can set the sensitivity of the Rotary knobs, and how a mouse drag changes the value relative to the rotary's current value versus the position clicked on the LinearBarVertical.  What are some ideas to changed the LinearBarVertical slider so that it has these features?


Edit: This was a lot simpler than I made it out to be. Just took a bit of thinking. Thanks for reading. For curious readers, I overrode the mouseDrag event in a new class.