Bug 151959 inappropriate screen operation
steps to reproduce: - create a report - add a grid item (3x3) - switch to Outline view - expand the grid item to see its rows and cells - select the grid item, and drag it into any of its own cell expected behavior: - is it an invalid screen operation? if it is, it should be banned actual behavior: - the grid item was disappeared surprisingly
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* reside in the {@link Module Module}.
 * <p>
 * An element also has a <em>display name</em> that is shown to the user. The
 * display name is optional, and is represented by a system property value. If
 * not provided, then the user sees the name. The display name is localizable.
 * Localized names are important for elements used in templates when the users
 * of the templates are international.
 * <p>
 * Members and classes in the name system include:
 * <p>
 * <ul>
 * <li>The {@link #setName}method.</li>
 * <li>The {@link #getName}method.</li>
 * <li>The {@link NameSpace NameSpace}class.</li>
 * </ul>
 * 
 * <h3>Containment</h3>
 * 
 * The overall report design organizes design elements into a hierarchy. All
 * elements except the report design itself are <em>contained </em> within some
 * other element: the <em>container </em>. The contained element is the
 * <em>content
 * </em>. (Note: the usage of the term container in this
 * discussion is more generic than the Container element in the report design.
 * The Container element is a container, but other elements are as well.)
 * <p>
 * The details of the containment are specific to each element type. For
 * example, a Container element has an ordered list of content elements. The
 * design has a named list of styles, and an ordered list of sections. As a
 * result, the implementation of the container-to-content relationship must be