Thanks for the heads up, hopefully this will address the bug. Keep in mind that beta versions are unstable by nature, intended for testing and detecting bugs - do not use them (e.g. refuse to auto-upgrade XQuartz to a beta version when asked), if you don't want to cope with this and need more stable...

I have the same problem in Snow Leopard with XQuartz 2.7.2_beta3 and _beta4, and Inkscape 0.48.2r9819. I think something changed in XQuartz that messes with wacom reporting of position. I downgraded to XQuartz 2.6 series and it works fine with that. The beta4 is particularly bad, it breaks my wacom ...