## Virtual Device Driver Reference for OS/2

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### Virtual Mouse Device Driver Services

For the virtual mouse device driver, the virtual video device driver provides a VDHRequestVDD function, as well as several direct interfaces for pointer drawing operations. The following VDHRequestVDD service is provided :

       VDHRequestVDD
       (
          HVDD  hvddVideo,
          HVDM  hvdm,
          INT   iFunc,       /* Virtual video device driver EVREQ_POSTMOUSE (4)   */
          PVOID pReqIn,      /* Undefined.                                        */
          PVOID pReqOut      /* Undefined.                                        */
       );                    /* Returns TRUE.                                     */

The virtual mouse device driver must return the address of a function that permits the virtual video device driver to obtain mouse position and button status during processing of the INT 10h, Query Light Pen function, when light pen emulation is enabled for the active DOS session. Also, whenever the DOS session changes video modes (including the initial mode change that takes place during DOS session creation), the virtual video device driver notifies the virtual mouse device driver of the new mode and screen dimensions.