subscripts being clipped

I have  seen Peter Below respond to subscripting questions several times
and his answer produces text with subscripts

When I subscript text in rich edit boxes, it gets clipped off at its
bottom.  I am assuming that this has something to do with a clipping
rectangle for a single line of text within a richedit control.  How
would one force rich edit boxes to make this clipping rectangle for a
single line of text taller without changing the text size?  Perhaps its
a function of internal leading?

Thanks in advance.

Robert Kennedy