In Lightroom CC, Develop>Gradient, the horizon swings hugely with small mouse movement. Very difficult to get to hold straight. Can you add micro movements with a key press, please?
Mac book pro, latest OS, latest Lightroom CC, Apple wireless mouse. I tried the alt key but not shift, so that's good information. However, I just want to be able to edge the "horizon " slightly, t'woild be nice feature. I have not found them easier to control anywhere along the horizon line and the farther from the centre, the steeper the angle goes. In fact half the time, it adds a new grad adjustment rather than moving the one I was working on.