Nextion. get current page/get last page

Hello friends

I am using a ESP32 and Nextion. I now try to create some kind of a popup-windows its works quiete ok. But now i ask myselft if its possible to get the last page, so if i close the popupwindow, i get back to my last page.

What i figured out so far: It is possible to track the the current page number if you read the global vairbale "dp" of the nextion. For example: int x = myObject.readNumber("dp"); (when you use the Easy NExtion libary).

I dont get it how you can get the last page id. Has anyone figured it out?

Thank you

I found also this. But i cant figure out how it should word:
https://seithan.com/projects/nextion-tutorial/#9

Maybe someone smarter than me knows more