Originally posted by iruit is possible to do this by hitting "submit move" without making a move - the notes should be saved (least they used to be)
When it's opponent's turn to move in a game I can type note in a notebook and save it using "Save notebook changes".
I couldn't find how to do the same if it's my turn to move. I mean without making a move. For example in case I have an idea that I'd like to note and analyze in depth later.