User-defined interfaces/pop-ups (not according to semantic model)

Hello all,
I have a question about the new Main UI. I updated my system from Openhab 2.5 to Openhab 3 a few weeks ago.

I have taken over my Basic UI and all works fine. As a next step I want to take advantage of the Main UI.
Unfortunately I can only edit the Semantic model in the text file (see following Link). If I understand it correctly, this creates the properties view.

Is there perhaps a way to create these views manually and thereby use user-defined icons, for example? I would like to be able to create the pop-up myself and then open it. Unfortunately, after several hours of searching, I have not been able to find any instructions on how to do this.

Thanks a lot!

You cannot significantly edit the system default popups for properties, equipment, etc. You can replicate them mostly, but only with a lot of extra work and (other items, rules, metadata etc.); it’s not really worth the effort and almost always more worthwhile to build a more tailored custom widget instead.

You can create custom list widgets for particular items that will then be included in the properties widget (see this post for examples).

If it is only custom icons you want, you can accomplish this in the default popups. They will function properly with correctly configured custom icons (see the docs for custom icons and custom dynamic icons).