This method is a special version of im_hittest for images that support
im_drawframe.  it asks an image if a point would be inside it if the image
was confined (scaled, clipped, etc.) to a rectangular bounds.  The return
value for this method is not explicitly defined.

This method uses a custom message structure:

    struct impHitTest
    {
        ULONG MethodID;    /* IM_HITFRAME */
        struct
        {
            WORD X;        /* Coordinates of point to test for hit */
            WORD Y;
        } imp_Point;

        struct
        {
            WORD Width;  /* scale, clip, restrict, etc. to these bounds */
            WORD Height;
        } imp_Dimensions;
    };

The imageclass dispatcher treats im_hitframe just like im_hittest,
ignoring the restricting dimensions.