NAME
        PRD_EDITPREFS - open the driver preferences window (V44)

   FUNCTION
        New drivers can have own preferences. This commands ask the driver
        to open a window to allow the user to change the prefs. Typically
        this is done with an doio() call.

        Every application should have a button "Driver Options..." (that
        calls PRD_EDITPREFS) in its printer dialog.

   IO REQUEST
        io_Message      mn_ReplyPort set if quick I/O is not possible.
        io_Command      PRD_EDITPREFS
        io_Flags        IOB_QUICK set if quick I/O is possible.
        io_TagList      a list of tags to specify more parameters

        The following tags are currently defined:

        PPRA_Window (struct window *)     a pointer to a window. this prefs
                window will open on the same screen and lock the window from
                user input.
        PPRA_Screen (struct screen *)     a pointer to a screen. that can be
                used if no window is open.
        PPRA_PubScreen (STRPTR) a name of a public screen that will be used
                to open the window. This can be NULL to use the default
                public screen.