Generating a own Popup

OK this worked and we got rid of the type error, if i start i now i get a attribute error: object has no attribute 'PREFS_' , i hope you dont get frustraded with me its all very new for me. I really appreciate your work with me. And it means a lot.

Ok I edited your handler file - I should have explained how to combine the code.
I didn't remove your popup code but it's not used. 
I used your modified qtdragon_hd.ui file
I made a sample vacuum panel based as a mainwindow with just an LED in it.

I confirmed this works on my system

This is interresting with your files i still get the error message:

AttributeError: 'MainPage' object has no attribute 'PREFS_'

If you run linuxcnc from a terminal then there should be more information on that error.

it's not enough for me to track it down

It worked, i forgot the handler in the /share/ path the Terminallog showed it wanted to load it. After deleting it started with the Button and i can Open the Pop-up too. Thank you very much for your Help and stamina with me

Excellent! Thanks for not giving up.

In this kind of trouble shooting details really matter.
qtdragon is not the same as qtdragon_hd, error messages need to be quoted exactly etc.

When you get everything finished I hope you post a pic of your creation.

Sure I will let you know about the finished Project