Jack Slocum on his blog posted about “A reusable component for resizing elements” —”The Resizable component has been completely refactored and has several new features.
I have put together a little list of examples below. This set of examples is in the RC2 download and is also available on the yui-ext Documentation Center site. A full list of configuration options and component reference is available here:

• Basic Example
• Wrapped Elements
• Pinned Handles
• Dynamic Sizing
• Preserve Ratio
• Transparent Handles
• Customizable Handles
• Snapping
• Animated Transitions
  Continue for more info and download....

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YUI Resizable Component