Beginner's question: Moving nodes to other flow tab

I am an absolute beginner and this might be a stupid question, but I can't figure out how to move some connected nodes to another flow tab. I tried selecting several connected nodes and dragging them onto another flow tab, but this results only in extremely difficult to edit messed-up layout. Follow-up to that would be: Is there a possibility to undo the last re-positioning operation?

You should be able to just highlight by selecting ( hold ctrl). Then just copy/cut and paste. To undo previous press crtl/Z

Or Cut/Paste to move them.