Select a table in one schema, click DBDiff - Select, then the same table in another schema and click DBDiff- Compare.
The help suggests that there should be diff done on the contents of the table.
However, only the table definition DDL is compared.
The log shows EDT violations from at org.jmeld.ui.StatusBar.init(StatusBar.java:78)
Tested on 3.4.0 and Snapshot-20121114_2001.