[arthur] Set the opacity when filling with axial gradients
This MR contains a small bugfix in the Arthur/QPainter backend, and a test for that fix. The test uses the example file from #178 (closed), but does not fix the bug reported there. As the example file is apparently hand-crafted just for the purpose of triggering the bug I don't see any obvious licensing issues.
I do not understand, however, where I am supposed to submit the example file. Can somebody enlighten me?