Bug 124620 Referenced Parameter icon should be invalid if the parameter in library is deleted
Description: Referenced parameter icon should be invalid if the source parameter in library is deleted. Steps to reproduce: 1.Create a library. Insert a report scalar parameter. 2.Create a report, use the above library. In the library explorer, pull the parameter to the data explorer view of report. 3.Open the library file, delete the parameter. Then reopen the report design file, the icon of parameter seems nothing happened. But if those operations happened in dataset, the icon of dataset in the report will be invalid. It is acceptable. Expected Result: The icon of referenced parameter should be invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* <dt><strong>Element type </strong></dt>
 * <dd>Inheritance only works between elements of the same type. One could say
 * that a derived element inherits the element type of the parent element. More
 * precisely, both the parent and derived elements have a type, and the
 * semantics of the application require that the element types be the same. It
 * is an error to extend an element of a different type.</dd>
 * 
 * <dt><strong>User-defined properties </strong></dt>
 * <dd>The user can define a custom property. All derived elements also have
 * that property.</dd>
 * 
 * <dt><strong>Custom behavior </strong></dt>
 * <dd>The user can define custom behavior by associating the element with a
 * Java class. Derived elements inherit this behavior.</dd>
 * </dl>
 * <p>
 * 
 * Inheritance does <em>not</em>, however, apply to the following:
 * <p>
 * <ul>
 * <li><strong>Name </strong>. A derived element does not inherit the name of
 * the parent component. If it did, then there would be two elements with the
 * same name, violating the rules about element name uniqueness.</li>
 * 
 * <li><strong>Parent element </strong>. A derived element necessarily has a
 * distinct value for the "extends" property than does its parent.</li>
 * </ul>
 * <p>
 * 
 * Members and classes in the inheritance system include: