An effort is underway to merge several well known Prototype based widgets into a single widget library built on top of the prototype / scriptaculous stack.  It’s already in a usable form combining the following widgets into a single js file.

• Dock
• Carousel
• Shadow
• Window

You can find it online at http://www.prototype-ui.com/

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• Prototype Carousel
• Prototype Window Class
• EXT JS