SETPREF ( nReg, nValue ) -> nOldValue

   ATTENTION! Only working in the registered version!

   With SetPref you can read and change SOUND&VISION's system
   configurations like Colors, Positions, SoundBlaster IRQ and such.

   Usually this should be handled by including SoundVis.ch in your
   application.

   Please do only work with predefined constants, like in Set.ch !


   PARAMETER:
   nIndex      Constant , chooses register to work with
   nValue      New Value or 0, if the register is just read

   RETURN VALUE:
   old value

   EXAMPLE:

          // set default row for 'Describe()' to 15
          // and save the old value to nOldRow
           nOldRow := SetPref( C_DESCROW, 15)