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
if ( operators == null || operators.length == 0 )
		{
			return;
		}
		Composite operatorsBar = new Composite( parent, SWT.NONE );
		operatorsBar.setLayout( new GridLayout( 2, false ) );
		operatorsBar.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		Label lable = new Label( operatorsBar, SWT.NONE );
		lable.setText( LABEL_OPERATORS );
		lable.setLayoutData( new GridData( 70, SWT.DEFAULT ) );
		Composite operatorsArea = new Composite( operatorsBar, SWT.NONE );
		operatorsArea.setLayout( UIUtil.createGridLayoutWithoutMargin( operators.length,
				true ) );
		SelectionAdapter selectionAdapter = new SelectionAdapter( ) {
			public void widgetSelected( SelectionEvent e )
			{
				Button button = (Button) e.getSource( );
				insertText( (String) button.getData( ) );
			}
		};
		for ( int i = 0; i < operators.length; i++ )
		{
			Button button = new Button( operatorsArea, SWT.PUSH );
			button.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
			if ( operators[i] != IExpressionProvider.OPERATOR_SEPARATOR )
			{
				button.setData( operators[i].insertString );
				String text = operators[i].symbol;
				if ( text.indexOf( "&" ) != -1 ) 
				{