VCL selection

[Caolán McNamara]

On Wed, 2024-03-06 at 20:00 +0000, Gwyn Ciesla wrote:
> Hi all! Fedora is looking at changing the default VCL plugin used for
> the interface for various desktop environments, specifically gtk4 for
> GNOME and kf6 for KDE. I'm able to choose the plugin by settting
> SAL_USE_VCL_PLUGIN, but when I have several installed and remove gtk3
> it defaults to X11, so I'm not sure how it makes that choice.

Probably vcl/source/app/salplug.cxx, where we set the order of plugins
to use, and if gtk4 was desirable as one to auto-use it would be
inserted into the list there beside "gtk3". Its absence from there is
why you have to "force" it via SAL_USE_VCL_PLUGIN

FWIW AFAIK the gtk4 accessibility experience is still subpar to the
gtk3 experience. And I think some of the obvious dropdowns, the font
and style ones in writer, don't render their entries as previews, only
as simple text.

Worth mentioning I guess is that the dialogs and other UI bits are
generally runtime converted from the basically-gtk3-format .ui files
into gtk4 equivalents. That sort of requires keeping to a uniform
pattern to make that conversion work. Which is basically what the
bin/ui-rules-enforcer.py is for. So if you get warnings/errors like:

GtkInstanceBuilder: error when calling gtk_builder_add_from_string

then the idea is; either that script can be run over the offending .ui
file and/or the script updated for whatever new problem has emerged and
then run over the offending .ui :-)