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
StyleCommand cmd = new StyleCommand( module, element );
		cmd.setStyleElement( obj );
	}
	/**
	 * Sets the shared style element for this element.
	 * 
	 * @param style
	 *            the handle to the shared style. If null, then the shared style
	 *            is cleared.
	 * @throws StyleException
	 *             if this element does not support a style.
	 * @see #getStyle()
	 */
	public void setStyle( SharedStyleHandle style ) throws StyleException
	{
		if ( style == null )
			setStyleElement( null );
		else
			setStyleElement( (StyleElement) style.getElement( ) );
	}
	/**
	 * Returns a handle to work with the style properties of this element. Use a
	 * style handle to work with the specific getter/setter methods for each
	 * style property. The style handle is not necessary to work with style
	 * properties generically.
	 * <p>
	 * Note a key difference between this method and the
	 * <code>getStyle( )</code> method. This method returns a handle to the
	 * <em>this</em> element. The <code>getStyle( )</code> method returns a
	 * handle to the shared style, if any, that this element references.