I think maybe I found an issue. 3.1.0 added a phase shift to gfx.setPattern, or maybe I misunderstood the documentation.
The documentation says default is (0,0). So technically I should get in 3.1.0 the same result as in 3.0.6 without specifying a phase shift. But I need to put a (0, 0) shift to get the same visual result as in 3.0.6.
In other words:
Result in 3.0.6 / To get this result in 3.1.0 and beyond you must write:
gfx.setPattern(pattern, 0, 0)
This is the result in 3.1.0 with unspecified phase shift.
gfx.setPattern(pattern)
Thank you 
Stephan