Yes I complied back from the official repo + your branch
I feel like there is maybe an issue with rotating the canvas... but I don't know where and how to check the values.
I did a simple test: drawing with a customised knife brush and not rotating barrel while drawing, I draw vertical stokes and horizontal stokes, and one is thin the other is thick...
Here is the brush:
And the result rotating the canvas, not the stylus:
Is canvas rotation influencing barrel rotation on the Art Pen ? they should be independant...
On other topics, yes having this visual feedback on cursor would be great bit I have no idea how to achieve that ;p. Can't libmypaint send the info to mypaint ? or maybe libmypaint should be in charge of drawing the cursor ?
Maybe in a second time ?
About Wayland, I had a crashy Xorg version theses last weeks because of several bugs (now solved), so that's why I tried Wayland. And Mypaint (git version) is the only drawing application supporting tablets on Wayland because it's based on GTK3.
So this bring me back to Mypaint after 2 years on Krita, and in the meantime I integrated the Art Pen in my workflow for inking, which brings me to you