As described at
there is a need for composite look. But it does not need to be exposed in API,
it is enough to just define the XML format of a file that should be stored on
SystemFileSystem that will recreated the right compositelook acording to
information in the file.
Partially implemented in
org.netbeans.modules.looks.CompositeLook.create but that is not the
final solution as discussed at
Moving Looks issues to dev 4.0
Composite look can be created by specifing context on filesystem.