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.ui/src/org/eclipse/birt/chart/ui/swt/interfaces/IUIServiceProvider.java
* Constant indicating an expression builder to input data bindings.
	 */
	public static final int COMMAND_EXPRESSION_DATA_BINDINGS = 1;
	/**
	 * Constant indicating an expression builder to input chart data point
	 * variables.
	 */
	public static final int COMMAND_EXPRESSION_CHART_DATAPOINTS = 2;
	/**
	 * Constant indicating an expression builder to input triggers except for
	 * value series.
	 */
	public static final int COMMAND_EXPRESSION_TRIGGERS_SIMPLE = 3;
	/**
	 * Constant indicating an expression builder to input triggers for value
	 * series.
	 */
	public static final int COMMAND_EXPRESSION_TRIGGERS_DATAPOINTS = 4;
	/**
	 * Constant indicating a common expression builder.
	 * @deprecated
	 */
	public static final int COMMAND_EXPRESSION = 1;
	
	/**
	 * Constant indicating an expression builder specifically for chart.
	 * @deprecated
	 */
	public static final int COMMAND_CHART_EXPRESSION = COMMAND_EXPRESSION_CHART_DATAPOINTS;
	/**