skencil arithmetic-errors occur all the time

[B Bobo]

 $ skencil
shared memory images supported
--- Calling RedrawMethod failed---
Traceback (most recent call last):
  File "/usr/lib/skencil/Sketch/UI/ruler.py", line 249, in RedrawMethod
    self.draw_ruler_horizontal()
  File "/usr/lib/skencil/Sketch/UI/ruler.py", line 281, in draw_ruler_horizontal
    DrawString(pos - tw / 2, y, text)
OverflowError: signed integer is less than minimum
---
[...]

This arithmetic error repeats endlessly all the time that skencil is being used.

It affects skencil from every recent version of Ubuntu from Maverick to Quantal in both 32-bit and 64-bit x86 architectures, all corresponding Ubuntu stable kernel versions and also latest development kernel.

Just as an example:
 $ skencil --version
0.6.17