zoomTimeline
Pinches a timeline's zoom ladder, holding the pinch's focal point still on the strip.
A one finger drag is left alone, so the strip underneath keeps scrolling normally. This only reads the gesture once a second pointer joins, and stops again the moment the pointer count drops back below two.
Parameters
state
The timeline the gesture zooms.
enabled
Whether the gesture is active. A host that owns the zoom level itself passes false, so the pinch does not fight it.