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
*            the module
	 * @param propName
	 *            name of the property to get. Can be a system-defined or
	 *            user-defined property name. Must be of the correct case.
	 * @return The property value, or null if no value is set.
	 */
	public Object getProperty( Module module, String propName )
	{
		ElementPropertyDefn prop = getPropertyDefn( propName );
		
		if ( prop == null )
			return null;
		return getProperty( module, prop );
	}
	/**
	 * Gets a property value given its definition. This version does the full
	 * property search as defined by the given derived component. That is, it
	 * gets the "effective" property value. The definition can be for a system
	 * or user-defined property.
	 * <p>
	 * The search won't search up the inheritance hierarchy if the non-style
	 * property is defined to not inherit. And style property won't be searched
	 * up the containment hierarchy if it'd defined to no inherit.
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param module
	 *            the module
	 * @param prop
	 *            definition of the property to get