Bug 200312 Chart Variables are still in the bottom right pane when select other categories [13]
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ExpressionBuilder.java
{
			return provider.getDisplayText( element );
		}
		public void addListener( ILabelProviderListener listener )
		{
		}
		public void dispose( )
		{
		}
		public boolean isLabelProperty( Object element, String property )
		{
			return true;
		}
		public void removeListener( ILabelProviderListener listener )
		{
		}
	};
	private IDoubleClickListener doubleClickListener = new IDoubleClickListener( ) {
		public void doubleClick( DoubleClickEvent event )
		{
			IStructuredSelection selection = (IStructuredSelection) event.getSelection( );
			if ( selection.isEmpty( ) )
			{
				return;
			}
			if ( event.getSource( ) == functionTable )
			{
				if ( selection.getFirstElement( ) instanceof Object[] )
				{
					Object[] inputArray = (Object[]) selection.getFirstElement( );