Apple Logic Pro 9 - Manual (Page 539)

A yellow guideline appears in the other track region as you jump from transient to
transient.
2 Release the mouse button to snap the flex marker to the highlighted transient marker.
Splitting Audio Regions at Transient Marker Positions
You can split an audio region into multiple regions at its transient marker positions.
To split a region at transient marker positions
µ
Control-click (or right-click) the region background, then choose Slice at Transient Markers
from the shortcut menu (or use the corresponding key command).
The selected region is split at every transient marker position.
Using the Flex Tool
You can use the Flex tool in the Arrange window’s Tool menu for quick access to basic
Flex Time editing functionality, without having to turn on Flex view using the View menu.
Note: If you try to use the Flex tool on a non-flex-enabled region, you are asked to choose
a flex mode for the region. Choosing a flex mode initiates a transient detection process
for any audio files that have not previously been analyzed.
539 Chapter 16 Flex Time Editing