Reconfirming bug on a september 22 zip build, on Windows XP
Popolon's comments suggest that this is a windows only bug,
and does not affect linux builds. It also only affects
tablets when they are used with the mouse, not the stylus
More details on behaviour:
Two pointer positions seem to be detected: A correct
position and a buggy one. When drawring with the free hand
or bezier tool, only the buggy position is used. With the
rectangle tool and other object drawing tools, the buggy
position is used for the starting point of the rectangle,
the true position for the opposite corner. As a result,
clicking with the rectangle tool doesn't produce a very
small rectangle with opposite corners in the same
positition. It makes a large rectangle with corners in the
true and buggy position.
Using a pen, not a mouse, on the table produces good
results. The postion of the pen is always correctly
detected and matches the position of the pointer on screen.
It seems this regressed around the time that pressure
sensitivity was introduced. Builds from the start of August
don't show this bug.
A possible interpretation of this is that inkscape is
querying the tablet at a low level for some operations but
is not doing so correctly and is interpreting the mouse as a
stylus. The buggy position is the position that would be
detected if the pad was in pen mode.