r=show_panel(ca)
r.addDataSelection(Overlays.Rect(None, Point(70,50), Dimension(20,40)))



ov = r.getDataSelection()
size =20
ov.width = 40 
ov.height = 80 
r.refresh()

ov.setPosition(Point(100,79))
r.refresh()

print ov.position.x,ov.position.x,ov.size.width, ov.size.height


r.addDataSelection(Overlays.Line(None, Point(20,50), Point(40,90)))
r.addDataSelection(Overlays.Crosshairs(None, Point(20,50), Dimension(-1,1)))
r.addDataSelection(Overlays.Crosshairs(None, Point(20,50), Dimension(1,-1)))