Function: posn-actual-col-row

Return the actual column and row in POSITION, measured in characters.
These are the actual row number in the window and character number in that row.
Return nil if POSITION does not contain the actual position; in that case
`posn-col-row' can be used to get approximate values.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions.