This is a gross hack that typedefs around between GdkRegion and
cairo_region_t and has some evil #ifdefs. This is going to die
immeditately once we can depend on cairo 1.10.
Before, the pattern offset was always relative to the widget, which
completely destroyed the stipples when the got scrolled in. Now we
simply set the shell's scroll offsets as cairo translation and
everything looks perfect.
Michael Natterer