the text for the run
the number of bytes (not characters) in text.
the analysis information return from pango_itemize()
the x offset (in Pango units)
location to store calculated byte index within text
location to store a boolean indicating whether the user clicked on the leading or trailing edge of the character.
Convert from x offset to character position. Character positions are computed by dividing up each cluster into equal portions. In scripts where positioning within a cluster is not allowed (such as Thai), the returned value may not be a valid cursor position; the caller must combine the result with the logical attributes for the text to compute the valid cursor position.