Bug 147687 Assert err happened with design ui
Run BIRT in workbench with argument -ea. Assert err happened when using design ui to open a design file.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dialogs/ExpressionTreeSupport.java
items[i].dispose( );
			}
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.ISelectionChangedListener#selectionChanged(org.eclipse.jface.viewers.SelectionChangedEvent)
	 * 
	 * Listen to JS editor method change.
	 * 
	 */
	public void selectionChanged( SelectionChangedEvent event )
	{
		ISelection selection = event.getSelection( );
		if ( selection != null )
		{
			Object[] sel = ( (IStructuredSelection) selection ).toArray( );
			if ( sel.length == 1 )
			{
				if ( sel[0] instanceof IPropertyDefn )
				{
					IPropertyDefn elePropDefn = (IPropertyDefn) sel[0];
					currentMethodName = elePropDefn.getName( );
					createContextObjects( currentMethodName );
				}
			}
		}
	}
}