Steps:
1. load facelet (*.xhtml) using Web Page editor (VPE)
2. within a particular existing RF tag say <rich:panel> enter a new line and start tag: "<"
3. enter content assist invocation: ALT-/
4. Observe error on bottom left of eclipse window: "<rich:panel> has no know child tags
5. this expands with the suggestion list, however, in the JBoss Tools HTML editor

This is JBDS 2.1.0.GA, Version: 3.0.2.v200909250150R-H168-GA