RichEdit: EM_POSFROMCHAR for bottom right corner

I need to know the bottom-right coordinates of a character
in a RichEdit control. Actually I calculate it by performing
the following steps:

    1. get the top-left coordinate by an EM_POSFROMCHAR
    2. calculate the character extent by a
       CDC::GetTextExtent() (called using a temporary
       Device Context)
    3. add the values obtained in steps 1 & 2

the main problem of this solution is in step 2: I need to
select the character for get the relative CHARFORMAT struct,
this cause a flickering problem with the selection.

There's someone that have a better idea?

Thank's in advance.