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
{
				return columnList.get( i );
			}
		}
		return null;
	}
	
	protected String getColumnName( Object obj )
	{
		return (String) obj;
	}
	
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.dialogs.Dialog#okPressed()
	 */
	protected void okPressed( )
	{
		try
		{
			if ( inputHandle == null )
			{
				FilterConditionElementHandle filter = DesignElementFactory.getInstance( currentItem.getModuleHandle( ) )
						.newFilterConditionElement( );
				filter.setProperty( IFilterConditionElementModel.OPERATOR_PROP,
						DEUtil.resolveNull( getValueForOperator( operator.getText( ) ) ) );
				
				
				Expression expression = new Expression( expButton.getDisplayExpression( ),