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/api/DesignElementHandle.java
public boolean isValid( )
	{
		return getElement( ).isValid( );
	}
	/**
	 * Determines whether to show an error item on the element or not. Show an
	 * error item if the element is invalid or has semantic errors, otherwise
	 * not.
	 * 
	 * @return true if the element has semantic error or the element is invalid
	 */
	public boolean showError( )
	{
		return hasSemanticError( ) || !isValid( );
	}
	/**
	 * Sets the status that identifies whether the element is valid or not.
	 * 
	 * @param isValid
	 *            the status to set
	 */
	public void setValid( boolean isValid )
	{
		getElement( ).setValid( isValid );
	}
	/**
	 * Justifies whether this element has any semantic error or not.
	 * 
	 * @return true if the element has any semantic error, otherwise false
	 */