Try looking at these two commands:
Quote: "dbSetDisplayMode
This command will set the screen display mode if it is available on the current graphics card. This command will not cause your program to fail on machines that do not support the resolution. It is recommended, however, that you check the availability of the display mode before using this command. You can use the dbCheckDisplayMode command to see whether the display mode is supported.
Syntax
void dbSetDisplayMode ( int iWidth, int iHeight, int iDepth ) "
and...
Quote: "dbSetWindowOff
This command will deactivate Windows Mode.
Syntax
void dbSetWindowOff ( void ) "
Full sceen is the max resolution that the user's display supports but you will still see the application window if you don't use the 2nd command I listed. I think so anyways never set an application to use 1680x1050 resolution in windowed mode
Use Google first... it's not rocket surgery!