Apple Motion 4 - Manual (Page 565)

There are times when the values of your keyframes may exceed the vertical resolution of
the graph. For example, as you stretch a keyframe, you can drag it so far that you force
the window to scroll.
When you click this button, Motion automatically rescales the graph both vertically and
horizontally so that your curve is entirely visible.
“Fit visible curves in
window” button
The values of your keyframes are not changed.
Auto-scale vertically: Click the “Auto-scale vertically” button (the magnifying glass in the
upper-right corner of the Keyframe Editor) to stretch the graph to fit all of the curves
currently in view.
“Auto-scale vertically”
button
565 Chapter 10 Keyframes and Curves