Does this help?
You love LibreOffice and OpenOffice, but you still use Visio to make drawings. Why? Because none of the shapes you need are easily available. Until now.
Custom OO Shapes is a repository of custom shapes you can use with LibreOffice and OpenOffice Draw. The following shapes are available:
UML Shapes Class, instance, package, component, assembly, collaboration, artifact, node, deployment, swim lanes (four variations), actor, accept event, action, activity final, decision, flow final, stop, initial node, parameter set, object node, condition, send signal, receive signal, frame, paths 24-Jan-2010 download (13.7 kb)