Richard,

The MessageBox function uses a second parameter that is made up of 3 distinct set of numbers:
1. 0 - 5 for buttons to appear
2. 16, 32, 48, 64 for the Icon to use (stop, question mark, etc...) and
3. 0, 256,512 for default button

one value from each group is added together to display a specific button(s), icon, and default.
A Yes/No button with a Stop icon and defaulting to Yes would be 4 + 16 + 0 OR 20.

If you include the Foxpro.h file in your form or class, these and the other values are named constants that you can use to simplify your function creation.
The above would be MB_YESNO + MB_ICONSTOP + MB_DEFBUTTON1

If you're lazy like me you might want to download the Message Box Wizard from C Lutions which is in the download area I believe...