Inspector: Click-drag to increase or decrease property values does not work with tablet/pen

[golddotasksquestions]

Godot version: 3.2.1

OS/device including version:
Win64, Wacom Intuos

Issue description:
With tablet and pen the values get stuck:

With mouse it works fine:

[stilobique]

Great to see this issue open, it's really important to all artist to have a good tablet support.
If some help to dev. with feedback are needed, i can give this feedback :) .

[Calinou]

Two possible reasons this bug can happen:

• The code expects mouse input to be relative once the mouse is captured, but tablet cursor positioning is absolute by design. I'm not sure how we can make it work while the mouse is still captured with absolute mouse coordinates.
• The code expects pressure to be set to 1.0 somehow.

[akien-mga]

CC @bruvzg

[bruvzg]

I can confirm this issue with wintab driver, but it's working correctly with winink driver, probably relative motion calculation issue.

[golddotasksquestions]

Winink is something a lot of people with tablet deactivate, because is terribly annoying and interfering all the time.