I know what they mean and your demo is not it.
You draw a rectangle, you push/pull it, you draw a rectangle on the wall, you push/pull through to the other side. Instead of it cutting a window it leaves it filled in with a face. If delete the face it deletes the entire face on that side. When you draw a line along the window edge it fills in the face and leaves the window empty.
I have no idea what causes it or how to replicate it consistantly but I just work around it.



I didn't ask help for english grammer n(oopz)"and" spells... I'll learn it later.Don't mind me, but others reply was much useful.. how does it matter if you can understand.. Iam sorry if you are outdated.. sorry anyway.