## Presentation Device Driver Reference for OS/2

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### GreOpenScreenChangeArea

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    Syntax
    Parameters
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    Glossary

Simulation support:

This function is mandatory for display drivers that want to be DCAF-enabled .

Description GreOpenScreenChangeArea allocates a data area internal to the display driver, in which the driver will accumulate screen changes. The function returns a 32-bit handle that is required to identify the area in GreGetScreenChangeArea and GreCloseScreenChangeArea calls.

    #define INCL_GRE_SCREEN

    #include <os2.h>

    #include <pmddi.h>

    HDC      hdc;     /*  Any device context handle. */

    PDC      pdcArg;  /*  Pointer to instance data. */

    ULONG    FunN;    /*  High-order word=Flags; Low-order word=NGreOpenScreenChangeArea. */

    LONG     rc;

    rc = GreOpenScreenChangeArea(hdc, pdcArg,

           FunN);