[Development] Deprecation of Qt Quick Controls 1

[Eike Hein]

Hi,

in addition, kde.org ships a qqc2-desktop-style for Controls 2 that
implements QStyle theming (it's an improved derivative of the code
used in qqc1) and has no other KDE dependencies. It's viable to ship
with an app, and available in most distributions as a system package
as well as inside KDE's Flatpak runtime. It's not been tested much
outside of X11, Wayland and win32, though.

We've mostly transitioned to qqc2 even for desktoppy things on the
back of this style, modulo some remaining gripes with the qqc2
combobox, IIRC.

(We've had a talk about upstreaming this work but it stalled a while
back.)


Cheers,
Eike