Squeak Smalltalk comes with many built-in objects and one of the most simple and straight forward is Flasher. It’s based on EllipseMorph and it flashes every 500 milliseconds. The default flashing color is red, but it can be changed. This object can also be seen in the objects window.
You can also find this object in the System Browser here.
And finally, here is my code examples that show how to create 2 new instances of Flasher class and show them in the world.
flasher := Flasher new. flasher openInWorld. greenflasher := Flasher new. greenflasher onColor: Color green. greenflasher openInWorld.