I'm almost sure I saw this once, I just can recall the sequence.
What I want to do is to hit C+something and then type but have my cursor stay in its current point and not move forward. Then I can somehow exit this mode (ESC) and type some text which will be inserted in between. This could be useful to type a prefix, a suffix and then the content without having to move the cursor back.
Example:
I would type "obj.method(" then press C+? then type "); // a comment", press ESC and type "1,2,3" without moving the cursor.
(what I do now is use C+SPC to set the mark, type and then press C+x C+SPC to go back to the mark)
TIA :)