In 1984, the Massachusettes Institute of Technology released the open-source window system known as X Windows System.  In 1987, the X11 protocol was finalized.  Flash forward 25 years into the future and Linux has been through several changes, but still runs its graphic system on the original X11 protocol.  While the X Window System has been through several changes including X.Org replacing X Windows, the phenomenal development behind X11 has kept it alive for many years.  Today, we have many new input devices and drivers available including Android.

Yes, that's right.  Android can now act as an input device for X.Org via the X.org input driver.  Developers at GIMPUSERS have created an Android application that you can simply install as an app on the device, as well as an accompanying driver for your desktop. Credit for this development goes to redforce.

He first developed the X.org input driver that is used for the desktop PC (running Linux in this case, which has a X display server running) to receive the touch events of your Android.

Then he made a native Android 4.0 app which acts as the input device for the PC. Pressure sensitivity of the tablet (if supported, for instance on the Galaxy Note 10.1 with stylus pen) is transmitted to the PC too.

Using this new application called "XorgTablet," you can use your tablet as a pressure-sensitive touch input device for your X Server.  If you would like to contribute to this ongoing development, you can get the application source and driver source from GitHub, test it out, and give feedback.

[Source: GIMPUSERS Article]