Problem

When using a tablet in a walk navigation, lifting and repositioning the stylus is handled as if the stylus has been moved to the new position in range. This makes the view rotate a lot, making the walk navigation only usable when the stylus doesn't leave the range height.

Proposed solution

First of all, we need to reset walk->is_cursor_absolute in walkEvent() when going from absolute to relative. Because currently, as long as a tablet has been used once, during the walk modal running, walk->is_cursor_absolute will stay absolute (even if a relative pointing device is used afterwards).

Second we'll need a (reliable) relative position event when a tablet goes out of range so the absolute coordinates get re-centered each time the tablet goes in range. For that we can send a dummy mouse move event on WT_PROXIMITY, when not inRange.

Not sure if this (second part) is an acceptable solution, maybe there's a more elegant one. Also, I have no idea how this behaves on the other platforms. I tested this with WinTab only. Triaging help on other platforms is appreciated.

Note that the proposed fix doesn't work well if the stylus went in range not over the Blender window. Those events may also be handled if this is a way to go.