[xubuntu-users] Xubuntu 20.04: qt5 development package

[Ralf Mardorf]

Maybe this one https://packages.ubuntu.com/focal/qt5-default with
it's dependencies or just https://packages.ubuntu.com/focal/qtbase5-dev
.

IIRC some development packages containing headers aren't available by
the regular repositories with the suffix -dev, instead they are
available by another source with another suffix. On the quick I
couldn't find any pointer by the Ubuntu wiki, the Ubuntu help or by
launchpad.