A Timeline Animation controls how Subcompositions, Groups, and Widgets animate in time and velocity. Timeline Animations are one of three methods to animate within a Composition, the other two are Update Animations and Behavior Animations.
1 - Animation Menu Tab
You can click, hold and drag the bar left and right as well as click hold and drag either end of the bar and shorten or lengthen an animation's duration.
Timeline Animations Represented by Colored Bars
2 - Two Animation Timelines
Enable two different Animation timelines for your In and Out moves by clicking on the "2 Timelines" button in the top portion of the Animation tab. This is useful if you want the overlay to leave the screen differently than it entered (and vice versa).
Enabling two Animation Timelines
If you wish to have the same animation for your in and out moves, don't access this feature.
3 - Animation Settings
The various Timeline Animation settings are accessed by clicking on the white lines icon on the Timeline Animation Bar. These settings include type, direction, duration and curve.
Adjusting Timeline Animation Settings
When operating your Composition from a Control Application, the Control Application can only control Timeline Animations that have been set a the root level of your Compostiion Tree structure. If you need Timeline Animations to play out in nested Subcompositions, you will need to use the Link Timelines feature.