NAME
        UpfrontLayer -- Put layer in front of all other layers.

    SYNOPSIS
        result = UpfrontLayer( dummy, l )
        d0                     a0     a1

        long upfrontlayer( long, struct layer *);

    FUNCTION
        move this layer to the most upfront position swapping bits
        in and out of the display with other layers.
        If this is a refresh layer then collect damage list and
        set the LAYERREFRESH bit in layer->Flags if redraw required.
        By clearing the BACKDROP bit in the layers Flags you may
        bring a Backdrop layer up to the front of all other layers.

        Note: this operation may generate refresh events in other layers
           associated with this layer's layer_info structure.

    INPUTS
        dummy - unused
        l - pointer to a nonbackdrop layer

    RESULTS
        result - TRUE   if operation successful
                 FALSE  if operation unsuccessful (probably out of memory)

    BUGS

    SEE ALSO
        graphics/layers.h