Drop GTK2 support in favor of GTK3

[Rene Engelhard]

On Tue, Aug 13, 2019 at 09:22:17PM +0200, Thorsten Behrens wrote:
> Caolán McNamara wrote:
> > https://gerrit.libreoffice.org/#/c/77405/ is my proposal to drop
> > LibreOffice's Gtk2 support in favor of the Gtk3 vclplug for LibreOffice
> > 6.4.
> >
> About time, yep. I just wonder if we should give it the usual
> one-release-cycle deprecation warning?

https://wiki.documentfoundation.org/ReleaseNotes/6.2 already has

"Feature removal / deprecation
General
The KDE4 VCL backend is deprecated and will be removed in the next
version.

The GTK+2 VCL backend is deprecated and will be removed in a future
version."

OK, there's the difference "next" vs. "in a future", but...

Regards,

Rene