extraDevice

configbody DCS::MotorViewEntry::extraDevice {
    if {$itk_option(-extraDevice) == $lastExtraDevice} {
       return

    }

    set m_extraDeviceReady 0
    if {$lastExtraDevice != ""} {
  ::mediator unregister $this $lastExtraDevice scaledPosition
    }
 if { $itk_option(-extraDevice) != "" } {
        set device $itk_option(-extraDevice)
        ::mediator register $this $device scaledPosition handleExtraDevice
 }
    set lastExtraDevice $itk_option(-extraDevice)
}