perhaps, this is already very simple and i just did'nt got that far into mod development right now.
It seems like a mess, if you want to create a self defined entity and tell the game to open a self defined new gui-window especially for it. It would be easier, if the Class LuaEntity would be extended with an attribute called gui (for example), which can be filled with a function to build the gui window and will be fired if the user clicks on the entity (like all the typical entities in the base game right now)
What i try to do in my mod:
- create a new entity, that looks like a constant combinator, but open another gui for reasons
- extend an existing entity gui, like the one of train stops with own gui elements
If there is an easy way to do this right now, i would be happy to get hints how to solve this

Greetings Ronny