Bug 122850 Table/list should not be able to be inserted in Master Page mode.
Description: Table/list should not be able to be inserted in Master Page mode. Steps to reproduce: 1. New a report and transfer to Master Page mode. 2. New a datasource and dataset 3. Drag a list/table to page header/footer, bind it to dataset and drag some columns inside. 4. Save and preview Expected result: Insert list/table item in master page should be forbidden. Actual result: They are allowed and preview showed "undefine" in page
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
assert getDefn( ).getProperty( propName ) == null;
		if ( userProperties == null )
			userProperties = new LinkedHashMap( );
		userProperties.put( propName, userProp );
	}
	/**
	 * Drops a user-defined property. The application must have previously
	 * removed all existing values for that property. The application must have
	 * previously validated that the user-defined property does exist, and is
	 * defined on this element.
	 * <p>
	 * Part of: User-defined property system.
	 * 
	 * @param prop
	 *            The user-defined property.
	 */
	public void dropUserPropertyDefn( UserPropertyDefn prop )
	{
		assert getDefn( ).allowsUserProperties( );
		assert userProperties != null;
		assert userProperties.get( prop.getName( ) ) == prop;
		userProperties.remove( prop.getName( ) );
	}
	/**
	 * Gets a user property definition defined on this class itself.
	 * <p>
	 * Part of: User-defined property system.
	 * 
	 * @param propName
	 *            The internal name of the user-defined property.