void PositionLocation (long start, float *x = NULL, float *y = NULL, Bool front = TRUE,
Bool eol = FALSE, Bool wholeLine = FALSE)
Returns the graphic locaiton of the given position. See End of Line Ambiguity (section 
)
for a discussion of eol. Either x or y may be NULL.
If front is TRUE, the top coordinate of the location is returned; if front is FALSE, the bottom coordinate of the location is returned.
The top y location may be different for different positions within a line when multiple fonts for graphic objects are used. If wholeLine is TRUE, the minimum top location or maximum bottom location for the whole line is returned in y.
Only valid when the buffer is viewed.