A color picker in javascript has nothing to do with php and ajax, just to clear that up.

What is loadSV and updateH, and $S? Whats all this?

If it comes down to this, I would pick jQuery, just write an extension or use the color picker plugin @ http://www.eyecon.ro/colorpicker/ / http://acko.net/dev/farbtastic and just modify that to support the amount of optional colors you want.

UPDATE I checked out, http://www.eyecon.ro/colorpicker/, it looks perfect for what you need, just modify anything visually and that's all you need.

Building a color picker by yourself, looks like a big challenge to do ( requires quite a bit of math to allocate every hex code out there ), speciously if you're trying to select optional colors.

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VillageIdiot can have my babbies ;d