How to ensure KDE apps have usable icons when run not in a Plasma session
There is a big issue with running our applications on non-Plasma desktops.
Like on Windows or macOS, where we fixed that with a lot of patching in Craft, per default our apps end up being more or less unusable by default, at least if you go with the default in most cases today dark theme they have.
See e.g. here Cinnamon with current Kate 24.02 (left side)
There are even no icons missing, but you have a wild mix of the native ones of Cinnamon, which are just a few and a lot of unreadable as non recolored ones from Breeze (that are only there as I have some Plasma installed).
The right side is after:
Later merged stuff to ensure we have Breeze and can fallback to it always:
As can be seen, that goes far above 'just Adwaita is broken for us'
To have really proper use of our engine we need do upstream https://codereview.qt-project.org/c/qt/qtbase/+/559108
The Adwaita 'a lot of icons are missing' is worked on in https://gitlab.gnome.org/GNOME/adwaita-icon-theme/-/issues/288 upstream. But even if there is some legacy stuff added, that will just be a stop-gap until we get our stuff done.