YDraw is a free Drawing software authored by Ramesh Yerraballi. It is licensed under GNU Lesser General Public License v3.0
For documentation click here: http://igoeco.github.io/YDraw/
The latest Windows 10 update breaks JPen's ability to acquire pressure sensitivity information from the Windows Tablet driver. You will need to install this WinTab driver update (Wintab_x64_1.0.0.20.zip) to restore pressure sensitivity. Without this update the pen will loose it smoothness.
JPen is old and has not been updated in a while. So, I rewrote the software to use a Windows native Java API called JWP. You can find this version under YDrawTool/YDrawJWP.jar. This may be the way forward on Windows but will not work on Mac OSX or Linux.