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
* defined in a subclass of this class.
 * <p>
 * However, all content elements have at most one container. And, all elements
 * (except the root) have a container. So, the content-to-container relationship
 * is modelled in this element base class.
 * <p>
 * Containers have one or more <em>slots </em>. See the
 * {@link org.eclipse.birt.report.model.metadata.SlotDefn}class for a detailed
 * description of slots.
 * <p>
 * Members in the containment system include:
 * <p>
 * <ul>
 * <li>The {@link #container}member that caches a pointer to the container
 * element.</li>
 * <li>The {@link #getContainer}method to get the container element.</li>
 * <li>The {@link #setContainer}method to set the container element.</li>
 * <li>The {@link #getSlot}method returns a slot within a container.
 * <li>The {@link ContainerSlot},{@link SingleElementSlot}and
 * {@link MultiElementSlot}classes that represent slots.</li>
 * </ul>
 * 
 * <h3>Change Notification</h3>
 * 
 * Any given element may be "visualized" in multiple places in the user
 * interface. If the user changes the element, all the affected parts of the UI
 * must be updated. The notification system is responsible for these updates.
 * <p>
 * The notification system allows any number of {@link Listener}objects to
 * subscribe to receive change notifications for an element. Notifications are