Considering to re-license the Windows Ink support code as BSD 2-Clause

[Alvin Wong]

Dear all,

I have been told by multiple people that OpenToonz developers would
like to make use of the Windows Pointer Input Message (Windows Ink on
Windows 8 or above) support code files
(libs/ui/input/wintab/kis_tablet_support_win8.h and
libs/ui/input/wintab/kis_tablet_support_win8.cpp) that I wrote for
Krita, but couldn't due to Krita being GPLv2+ and OpenToonz being
licensed in BSD 3-Clause, Currently Drawpile has already adopted these
code with no issues since Drawpile is GPLv3.

I would be fine with allowing OpenToonz to use the current version of
the code in BSD 3-Clause licence, but this would seem short-sighted
since future changes of the code in Krita wouldn't make it into
OpenToonz without further permissions, and it would get more
complicated if other developers make changes.

Therefore, I am considering to re-license these two files within the
Krita repo as BSD 2-Clause (BSD 3-Clause is not allowed according to
KDE policies), and request that in the future other developers who
make changes to these two files within Krita should agree to license
their changes as BSD 2-Clause. A problem with this approach is that if
Drawpile, OpenToonz or other derivatives make other functional changes
under a more restrictive licence (e.g. GPL or even BSD 3-Clause), they
can't be backported to Krita without explicit permission. It would
also mean that even closed-source software can use code from these two
files, though I don't have problems with this. Drawpile and others can
still continue to use the current or older versions of the files (and
derivatives of it) as GPLv2+, though it would get a bit complicated if
they wish to include any future changes.

The process should be as simple as me making a commit to change the
license comment blocks in these two files.

Are there any technical issues with this approach, or did I show any
misunderstanding in the previous paragraphs?

I would like to have this done in no more than a week, so if there are
any concerns please raise them as soon as possible.

Best Regards,
Alvin Wong

CC: OpenToonz develoeprs John Dancel and Jeremy Bullock and Drawpile
developer Calle Laakkonen