Currently the Vertical Scale Adjusts its self automatically.
This is good keep it like that.
It would be very nice if you could add a "Tick box" to fix the Vertical Scale at it's current scale when you tick the box.
Then when you untick the box it goes back to auto scaling.
I think this would improve it, and help people to visualize the readings without having to keep checking what values are given on the left.
Hope you understand what I say.