In the DB Explorers, i would double click the Tables to expand the table tree. Then I I double click on a table to see the Column, Comment, Data... tabs. At the top of this window, there is a dropdown to select another table. This drop down is blank for me when connection to my 11gr2 database with my 10g client.
Workaround:
None
Status:
Waiting for fix in future release of SQL Navigator for Oracle.