>Is there any way to increase the font size of message text in a messagebox?

AFAIK, this is controlled by the Appearance tab in the Display ControlPanel.
The best way around it is probably to write your own modal form that mimics the
behavior of the messagebox.

#include \vfp\foxpro.h

nOptions = MB_ICONQUESTION + MB_YESNOCANCEL + MBDEFBUTTON1
cMessage = "Save this record?"
cCaption = "MyApp"
lnRetVal = IDNO

DO myMsgBox WITH cMessage, nOptions, cCaption TO lnRetVal

IF lnRetVal = IDYES
   * something or other
ENDif

and in the form, have a very large label with WordWrap = .T., and an OleControl
to show the icon, and all 7 or so buttons defaulting to Visible = .F. until
the Form.Init finds out which ones you want and sets focus as appropriate...