public void setSelectedItem(Object obj) {
   selectedSourceLevel = (obj == null ? null : ((SourceLevelKey) obj).getSourceLevel());
   fireContentsChanged(this, -1, -1);
   SourceLevelKey key = (SourceLevelKey) obj;
   if (key != null) {
     props.setJavacSourceLevel(key.getSourceLevel().toString());
     props.setJavacTargetLevel(key.getSourceLevel().toString());
   }
 }