I use a Dell premium active pen (PN579X) on an XPS 9575 laptop (The laptop uses Wacom active pen tech). I have found that when I first open Painstorm, it does not recognize the pen direction and tilt of the pen. But if I then close and re-open Painstorm, it will then recognize the pen direction and ...

I recommend you consider providing support for Windows Ink. In my case I have a Dell 9575. The digitizer is Wacom tech, but I have found that in other programs (such as Krita) the pen doesn't work well until I have it switched to Windows Ink. In the case of Paintstorm, using the direction of the til...