In Release 2, whenever a new screen is created, Intuition also creates an
auxiliary data structure called a drawinfo.  the drawinfo structure
provides information Intuition uses to support the new 3D look of Release
2 and  specifies graphical information for applications that use the
screen.  The information includes such items as aspect ratio (resolution),
font, number of colors and drawing pens.


struct DrawInfo
{
    UWORD       dri_Version;    /* will be  DRI_VERSION                 */
    UWORD       dri_NumPens;    /* guaranteed to be >= numDrIPens       */
    UWORD       *dri_Pens;      /* pointer to pen array                 */

    struct TextFont     *dri_Font;  /* screen default font              */
    UWORD       dri_Depth;          /* (initial) depth of screen bitmap */

    struct {    /* from DisplayInfo database for initial display mode   */
        UWORD   X;
        UWORD   Y;
    }           dri_Resolution;

    ULONG       dri_Flags;              /* defined below                */
    ULONG       dri_Reserved[7];        /* avoid recompilation ;^)      */
};


Before an application uses fields in the drawinfo structure, it should
check the version of the structure to ensure that all fields are
available.  If the field dri_Version is greater than or equal to the
constant DRI_VERSION that the application was compiled with, it can be
assured that all fields in DrawInfo that it knows about are being
supported by Intuition.

 the pen specification in drawinfo 
 the font specification in drawinfo 
 cloning a public screen (workbench)