The resource "Open" action appears to be suppressed within the Project Explorer view in CCSv5.1 M8. As a consequence, double clicking on most types of file resources within the Project Explorer achieves nothing. As a workaround, you can drag the file into the editor pane to open it. This issue is observed within all perspectives (not just the CCS Edit perspective) and makes it difficult to use CCS v5.1 as a general purpose Eclipse workbench.