Re: what is the CSSValue.CSS_CUSTOM type for?

David Flanagan wrote:
> 
> The CSSValue interface defines a constants CSS_CUSTOM, which the spec
> describes as "The value is a custom value".  Unfortunately, I can't any
> mention of "custom values" in the index of the DOM CSS spec, or of the
> CSS2 spec itself.

This is an extension mechanism for the CSS OM. If a CSS OM extension wants
to provide its own methods for a CssValue, the type of the CssValue is
CSS_CUSTOM.

> Can someone tell me what this means and give an example of when it might
> be used?  If I have a CSSValue object that represents a custom value,
> can I do anything with it other than query its cssText property?

You'll find an example in the SVG spec, section B.6.4:
http://www.w3.org/TR/SVG/svgdom.html#ExtendedInterfaces

Philippe