blinking

$canvaseditor blinking on: switches background blink mode on
$canvaseditor blinking off: switches background blink mode off

obj method canvaseditor blinking {{onoff on}} {
  blink [my canvas] stop
  if {$onoff} then {
    blink [my canvas] -color1 navy -color0 wheat -interval 15
  } else {
    $self elements blink off
  }
}