Bug 198031 Legend interactivity does not work correctly for drill-throughs
Under Value (Y) Series enable interactivity for the event "Mouse Click" Set action to Hyperlink The type of the hyperlink is Drill-through and the target is the a sub-report Pass parameter to sub-report as row["value_of_the_legend_item"] Suppose there are 3 values, x,y and z No matter which legend item you click (x, y or z), z gets passed as param to the subreport
chart/org.eclipse.birt.chart.reportitem.ui/src/org/eclipse/birt/chart/reportitem/ui/ChartReportItemBuilderImpl.java
* 
	 * @param builderCommand
	 * @return category style
	 */
	private int getExpressionBuilderStyle( int builderCommand )
	{
		if ( builderCommand == COMMAND_EXPRESSION_DATA_BINDINGS )
		{
			return ChartExpressionProvider.CATEGORY_WITH_BIRT_VARIABLES
					| ChartExpressionProvider.CATEGORY_WITH_COLUMN_BINDINGS
					| ChartExpressionProvider.CATEGORY_WITH_REPORT_PARAMS;
		}
		else if ( builderCommand == COMMAND_EXPRESSION_CHART_DATAPOINTS )
		{
			return ChartExpressionProvider.CATEGORY_WITH_CHART_VARIABLES;
		}
		else if ( builderCommand == COMMAND_EXPRESSION_TRIGGERS_DATAPOINTS )
		{
			return ChartExpressionProvider.CATEGORY_WITH_BIRT_VARIABLES
					| ChartExpressionProvider.CATEGORY_WITH_CHART_VARIABLES
					| ChartExpressionProvider.CATEGORY_WITH_COLUMN_BINDINGS
					| ChartExpressionProvider.CATEGORY_WITH_REPORT_PARAMS;
		}
		else if ( builderCommand == COMMAND_EXPRESSION_TRIGGERS_SIMPLE )
		{
			return ChartExpressionProvider.CATEGORY_WITH_REPORT_PARAMS;
		}
		return ChartExpressionProvider.CATEGORY_BASE;
	}
}