If you add or delete a row to or from a section, or if you change the geometry 
of any of the rows in that section, you may need to update the bounding box for 
that section. 
 
XkbComputeSectionBounds 
examines all the rows of the 
section 
and updates the bounding box of that section so that it contains all rows.
XkbComputeSectionBounds 
returns False if any of the arguments is NULL; otherwise, it returns True.