Bug 193245 Should block user to set content type property on the child element
After we switch from the slot to content element type property, all the rules that we applied to the slot before should be applied to the content element type property. When an element is extended from the library element, it should not be allowed to change the child element structure. So, when user call setProperty() to set the value of the content element type property, Model should throw out exception.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/command/PropertyCommandTest.java
/**
	 * Invoke
	 * {@link org.eclipse.birt.report.model.command.PropertyCommand#insertItem(MemberRef,IStructure, int)}
	 * to test InsertItem method.
	 * <p>
	 * Invoke
	 * {@link org.eclipse.birt.report.model.command.PropertyCommand#removeItem(MemberRef, int)}
	 * to test RemoveItem method
	 * <p>
	 * Test Cases:
	 * <ul>
	 * <li>insert new item named InsertAndRemove</li>
	 * <li>remove this new item</li>
	 * <li>undo and redo those two operations</li>
	 * <li>remove item from null structure list</li>
	 * </ul>
	 * 
	 * @throws Exception
	 */
	public void testInsertAndRemoveItem( ) throws Exception
	{
		StyleElement style = design.findStyle( "Style2" ); 
		
		List rules = (List) style.getProperty( design, Style.MAP_RULES_PROP );
		assertTrue( rules.size( ) == 2 );
		
		MapRule rule = new MapRule( );
		PropertyDefn propDefn = (PropertyDefn) rule.getDefn( ).findProperty(
				MapRule.DISPLAY_MEMBER );
		rule.setProperty( propDefn, "InsertAndRemove" );