composition at `stop_pos', and this is an automatic compositoin.
If negative, this is a static composition.. */
int ch;
+ /* If this an automatic composition, how many charaters to look back
+ from the position where a character triggering the composition
+ exists. */
+ int lookback;
/* If non-negative, number of glyphs of the glyph-string. */
int nglyphs;
/* Number of characters and bytes of the current grapheme cluster. */