I've searched and searched and haven't found any mention of this problem anywhere, so it must just be me overlooking something obvious, but:
I'm using a Surface Pro II, and I if I rest my palm on the screen while drawing with a stylus, both touches register and drawing is essentially impossible. In most other programs (not just other drawing programs, but in general,) if the stylus is near enough to the screen for the computer to track its motion, all touch input is blocked out, in order to prevent this kind of conflict. I can't draw at all, really, if I can't rest my hand on the screen.
Is this a driver issue? I updated from Win 8 to Windows 10 and searched around for relevant drivers, but I haven't found anything relevant.
The particular stylus is a lifebook, if that makes a difference.