Hi Geoff,
Left-click-drag the value knob up/down to change the value. The faster you move the mouse the more the value will change for a given cursor travel distance. If you look at the GIF animation I shared previously I am just dragging the Stamp Size parameter up and down, and when holding SHIFT it changes from 0.0mm to 250.0mm very quickly with a single quick mouse motion.
There is a possibility that your mouse cursor speed is set extremely low in Windows, which will require moving the mouse very fast and far to get a cursor speed that will produce the exponential value change - but then interacting with the 3D view and manipulating layers by their handles would also be very slow I would imagine.
PixelCNC's UI assumes that your cursor can be moved from one side of your screen to the other without picking up the mouse, with a single wrist motion. If your cursor sensitivity is turned down I can also add an option to the UI Settings dialog for tuning the sensitivity when interacting with everything, if you think that would help.
Let me know what you think. :]
- Charlie
