To translate all occurrences of an attribute to another attribute, the
maptags() function is used.

For Release 2, the third parameter of this function is always TRUE (tags
remain in the array even if they can't be mapped).

    struct TagItem map_list[] =
    {
        /* Original     New */
        {MGA_LeftEdge,  GA_LeftEdge},
        {MGA_TopEdge,   GA_TopEdge},
        {MGA_Width,     GA_Width},
        {MGA_Height,    GA_Height},

        /* Terminate the array */
        {TAG_END},
    }

    /* Map the tags to the new attributes, keeping all attributes that
     * aren't included in the mapping array */
    MapTags(tags, map_list, TRUE);