During the creation of a CSub, I mistakenly closed the initial open subwindow Plc session while leaving edit mode in the main window.

This has left my PLC main window in a bad state - when I try to open the CSub subwindow, it says "Subwindow does not exist". If I try to delete the CSub, I cannot save my Plc session (console message "%LDH-E-HAS_CHILD, object has child").

How do I recover from this mistake?

Never mind - I found that I can delete the CSub object outside of the Plc program in the Configurator, and if I then open the PLC main window, save it, close and re-open it, I can create a new CSub with a different name.