JSF 2.0 allows the following tags to refer to the resources:
h:outputStylesheet name="RESOURCE_NAME"
h:outputScript name="RESOURCE_NAME"
h:graphicImage name="RESOURCE_NAME"

This is quotation from the JSF 2.0 Documentation (http://java.sun.com/javaee/6/docs/api/javax/faces/application/ResourceHandler.html ):
The default implementation must support packaging resources in the web application root under the path
resources/<resourceIdentifier>
relative to the web app root.
For the default implementation, resources packaged in the classpath must reside under the JAR entry name
META-INF/resources/<resourceIdentifier>
<resourceIdentifier> consists of several segments, specified as follows.
[localePrefix/][libraryName/][libraryVersion/]resourceName[/resourceVersion]

The HTML Editor supports OpenOn only for the resources which are placed in WEB_ROOT/resources/[libraryName/]resourceName .
There is no support for:
1. JAR files
2. Locale
3. Library version
4. Resource version
The support should be added.

Also see: JBIDE-5382.