Comment 4 for bug 172219

I, too, would expect the nib to be 90 degrees different from the result in Inkscape. Note that this is not merely a matter of surprise, it makes the difference between useful or not for writing classical scripts.
Could the value in the nib angle input field (labeled "Angle:" in English locale) be added to the value calculated from the tablet pen tilt? That way,
 - there is no need for an additional check box
 - users can have it their way
 - and you could even simulate a slant-cut nib fountain pen, as used by left handed people for classical scripts.
(Even if this isn't the right place for that: Inkscape is among the most marvellous tools I know! Keep going!)
Inkscape 0.46 + 0.47pre3, Wacom XD-0608-U (Intuos 2 DIN A5), Windows XP SP3