What is the purpose of the "Undo Zoom" button on the graphs on the summery page?

[rcd]

I was looking for a way to zoom out on the list of graphcs on the summary page in order to be able to screenshot all 4 graphs (cpu, memory, network and disk-io) but the closest thing is this "Undo Zoom" button, that kinda suggest there should be a way to Zoom the graphs?

 

[leesteken]

I was looking for a way to zoom out on the list of graphcs on the summary page in order to be able to screenshot all 4 graphs (cpu, memory, network and disk-io) but the closest thing is this "Undo Zoom" button, that kinda suggest there should be a way to Zoom the graphs?

Click and drag to select a rectangle to zoom into.