Hi Ferencz,

> I'm Ferencz Kovacs and I'm currently working on LabPlot for GSOC 2019.
>[...]
> Do I have to register the categories first somewhere? Thank you in advan=
ce.
> Every tip is more than welcome.
Yes, this has to be registered. Similar to how it was done here for exampl=
e:
https://phabricator.kde.org/T9980

Let's discuss this in more details in another email thread we have on this
already and sorry for being not able to reply earlier to you there.

Regards,
Alexander