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Regions may be modified by performing logical operations with rectangles,
or with other regions.

    Reuse Your Rectangles.
    In all of the rectangle and region routines the clipping rectangle
    is copied into the region.  This means that a single clipping
    rectangle (Rectangle structure) may be used many times by simply
    changing the x and y values.  The application need not create a
    new instance of the Rectangle structure for each rectangle added
    to a region.

For instance:

    extern struct Region *RowRegion;  /* created elsewhere */

    WORD ktr;
    struct Rectangle rect;

    for (ktr = 1; ktr < 6; ktr++)
        rect.MinX = 50;
        rect.MaxX = 315;
        rect.MinY = (ktr * 10) - 5;
        rect.MaxY = (ktr * 10);

        if (!OrRectRegion(RowRegion, &rect))

 Rectangles and Regions    Regions and Regions