View Category:Mixing Window -> Segment Snapping Icon
When the Segment Snapping button is enabled and a segment is being move or resized, some resistance to the movement of the segment will be experienced as the segment approaches the start or end position of an adjacent segment.
Also, as the segment approaches an adjacent segments extremity, a blue icon will be displayed on the moving segment to accurately show the contact placement position. If the mouse is released at the point of resistance, when the blue icon is also displayed, the moving segment will jump to the placement position indicated by the blue icon. This facility allows for precise placement of segments and effects grids.
Watch Video: Segment Snapping Icon (Mixing Screen Video Part 1)