Three points define a "Quick" Parabola.

You can move the points around and press "Activate" to see the parabola

Two questions:

How is it made?

and (this one I want to know)

Can all parabolas be quick parabolas?

If you don't see the diagram then you can't do this.

Press the red "X" at the bottom right corner of the diagram to remove the parabola...