Blender Version
Broken: dc316f72b37
Short description of error
This has been a long running bug in Blender. When pressure sensitivity is enabled on brush size for either the Snake Hook, Grab or Rotate brush, it doesn't work. Even when the option is enabled and the brush gives visual feedback on the amount of pen pressure, it won't change the influence of the brush.
Size pressure is not supported by these brushes, though this does not appear to be communicated correctly in the UI.
What do you expect pressure sensitivity for radius to do? For grab and rotate it doesn't make a lot of sense to me, the radius defines the initial area that is grabbed and I wouldn't expect that to change while dragging. For snake hook I can imagine it working, would need to check if there if fails in some way when enabling pressure there.
Ah ok!
I don't think it makes sense for it to change while dragging but as an initial dynamic size it could be very useful sometimes. When you are dragging out multiple shapes with the grab brush in succession and each is supposed to have a slightly different size, currently you would have to adjust the size radius every time.
One problem that I can see is that the pressure starts off very small usually. Because of that, if users have the size set as a unified setting for all brushes they might not want pressure sensitivity enabled for grab, snake hook and rotate. That could be a bit disrupting while working. There could be an extra option in the "unified settings" that works individually for pressure sensitivity, but that's a different issue.
Maybe instead there's a way of using the pressure sensitivity input from just a moment later when using it on those brushes but that could make the brush lagging behind for split second.
What do you think?
Maybe this is more than a bug fix. This should be tested and discussed further but for now maybe removing the option for those brushes would cause less confusion.
It is better to discuss this in a design task: D6603
So closing this as it is not a bug.