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