Or, more generally:
Code:
on run
tell application id "OGfl"
tell front window
set refGraphics to a reference to graphics of its canvas
set lstSeln to selection
repeat with oSeln in lstSeln
my BringToFront(oSeln, refGraphics)
end repeat
end tell
end tell
end run
on BringToFront(oGraphic, refGraphics)
move oGraphic to beginning of refGraphics
end BringToFront
on SendToBack(oGraphic, refGraphics)
move oGraphic to end of refGraphics
end SendToBack