I´m not that often using zypper, thus I added the 42.3 source repo to YasT2:
https://download.opensuse.org/source/distribution/leap/42.3/repo/oss/
The strange thing is now, within YaST2 not a singe .src.rpm is shown when I try to browse that repo… Yes, I activated it.
And there seem to be no option/need in YaST2 to explicitly show .src.rpm as far as I can see.
How the heck can I now browse the src rpm repo with YaST2? I´m not aware of having made anything wrong…
Or is the source repo not meant to be used with YaST2 !?