k3b default theme 'quant' moved to k3b-extrathemes in Ubuntu Bionic

Steps to reproduce the bug :
On otherwise-empty system, install 'k3b' package with 'apt install'
Run 'k3b' and see it starting up with empty splash screen and without other graphical controls

Workaround in Bionic : install 'k3b-extrathemes' package

In Xenial and Trusty, 'quant' theme was in 'k3b-data' package. From 'packages.ubuntu.com' I see that it was moved into 'k3b-extrathemes' since Artful (or some already-discontinued Yakkety/Zesty distro before Artful)

Proposed resolution : make 'k3b' depend on 'k3b-extrathemes', not just suggest it
or : move default 'quant' theme back into 'k3b-data' where it was before.