Bug 312859 The list of operator for Chart filter does not provide 30 visible items
chart/org.eclipse.birt.chart.reportitem.ui/src/org/eclipse/birt/chart/reportitem/ui/dialogs/ChartCubeFilterConditionBuilder.java
public void widgetSelected( SelectionEvent e )
			{
				int count = valueList.size( );
				if ( count > 0 )
				{
					valueList.clear( );
					tableViewer.refresh( );
					updateButtons( );
				}
				else
				{
					delAllBtn.setEnabled( false );
				}
			}
		} );
		addExpressionValue.addModifyListener( new ModifyListener( ) {
			public void modifyText( ModifyEvent e )
			{
				checkAddButtonStatus( );
				updateButtons( );
			}
		} );
		addExpressionValue.addListener( SWT.Verify, expValueVerifyListener );
		addExpressionValue.addListener( SWT.Selection,
				expValueSelectionListener );
		refreshList( );
		addExpressionValue.setItems( popupItems );
		parent.getParent( ).layout( true, true );
		return 1;
	}