update of message area

Hello,

I am using a capi  window that contains  one or several opengl 
subviews with a message area created with the initarg:
:message-area

The message area is updated periodically using the 
titled-object-message accessor.

The system works otherwise fine, except that each time the message 
area is updated the complete window is redrawn.

Is it possible to redraw only the message area without having to draw 
the whole window?

I am using LispWorks for Macintosh 4.3.6 on Mac OS X 10.2.8.

Regards,

Mikael