JSF Libraries could have a facelets taglib xml file like this: (see myfaces tomahawk for jsf 2.0 1.1.10)

<facelet-taglib xmlns="http://java.sun.com/xml/ns/javaee"
              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
              xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facelettaglibrary_2_0.xsd"
              version="2.0">
              
    <namespace>http://myfaces.apache.org/tomahawk</namespace>
    <composite-library-name>org.apache.myfaces.custom</composite-library-name>

    <!-- Component Tags -->
    <tag>
        <tag-name>commandButton</tag-name>
        <component>
            <component-type>org.apache.myfaces.HtmlCommandButton</component-type>
            <renderer-type>org.apache.myfaces.Button</renderer-type>
        </component>
    </tag>

Take a look on the part that specifies a composite-library-name. In theory it is possible to have libraries with normal jsf artifacts (components, converters, validators, behaviors, facelets tags) and composite components under the same namespace (in this case http://myfaces.apache.org/tomahawk ). 

Netbeans code completion does not take into account this fact and ignore the additional entries, so when I try to use this library, the code completion only detect composite components (t:inputHtml), and not the other ones.