Open Source: Yes.
Source Code: https://github.com/maoschanz/drawing
License: GPLv3, https://github.com/maoschanz/drawing/blob/master/LICENSE
Distributions which include this package: I think currently none, however the developer intends to get it packaged once it is stable.
Reason for inclusion: Linux distros in general (not just Solus) need a simple drawing app for people who do not intend to do serious image editing.
Currently this task is more of a holder, until an official stable version comes out, but feel free to check it out (things are currently working great for me).