DSP Robotics Support

Anybody ever gimcracked a timer or such, that would, when hit with a boolean True, alpha-fade a GUI element, say a filled rectangle, from transparent to opaque over the course of a few seconds?

Attached are a few example in one schematic.
This is all in green. You can use a Slide primitive, or get a little more complex with a timer.
I'm sure someone else can provide a ruby example, but it's beyond me.

Thanks so much - The simple one with the Slide prim does exactly what I wanted!