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 a hyper-link builder.
	 */
	public static final int COMMAND_HYPERLINK = 0;
	/**
	 * This method will be used by the Chart Builder UI to invoke the expression
	 * builder with any previously defined expression. The parameter may be null
	 * if a new expression is to be built.
	 * 
	 * @param sExpression
	 *            the expression to be displayed in the builder (after re-entry)
	 * @param oContext
	 *            the application-specific context used by the Expression
	 *            Builder for each invocation
	 * @param sTitle
	 *            the title to be used for the Expression Builder Dialog
	 * 
	 * @return The final expression string built by the user in the expression
	 *         builder
	 * 
	 * @deprecated use invoke( int command, String value, Object context, String
	 *             sTitle ) instead.
	 */
	public String invoke( String sExpression, Object Context, String sTitle );
	/**
	 * This method will be used by the Chart Builder UI to invoke the expression
	 * builder with any previously defined expression. The parameter may be null
	 * if a new expression is to be built.
	 * 
	 * @param sExpression
	 *            the expression to be displayed in the builder (after re-entry)