Resizing Swimlanes
You can resize swimlanes from their bottom edges, with the exception of the bottommost swimlane in a pool, which cannot be resized. Swimlanes must always be at least as large as their contents.
Important: A pool’s default dimensions are 100 pixels high by 700 pixels wide, horizontally oriented. A pool’s minimum dimensions are 100 pixels by 200 pixels. If you attempt to resize a pool to less than its minimum height or width, Designer resizes the pool to its default dimensions.
To resize a swimlane
1. Select the swimlane.
2. Click and drag one of the resize handles of the swimlane to resize it.