OK, – could it be the graphics card issue we are seeing from other people as well? If your graphics card is of a certain older type (haven’t found out exactly which ones) – it seems AP struggles with the line when drawing and undoing etc.
What graphics card do you have?
Another thing: If you want to switch Animation Paper to using Windows Ink (normally if pressure sensitivity isn’t working on touch screen computers) do this:
Find the file “qt.conf” (probably here C:\Program Files\Animation Paper\qt.conf). Delete it or rename it (to save it). Then launch Animation Paper again.
This will force Animation Paper to use Windows Ink. Later we will do a more elegant check box option. 😉
Hope this is of some help.