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
* @param module
	 *            the module
	 * @param propName
	 *            The name of the property to get.
	 * @return The property value as a string.
	 */
	public String getStringProperty( Module module, String propName )
	{
		ElementPropertyDefn prop = getPropertyDefn( propName );
		if ( prop == null )
			return null;
		Object value = getProperty( module, prop );
		if ( value == null )
			return null;
		return prop.getStringValue( module, value );
	}
	/**
	 * Returns the value of the property in a localize format. Formats dates and
	 * numbers in the form according to the current locale. Converts choices and
	 * colors to their localized display names. Returns the localized display
	 * name for an element reference, etc.
	 * 
	 * @param module
	 *            the module
	 * @param propName
	 *            the property name
	 * @return the localized display value of the property
	 */
	public String getDisplayProperty( Module module, String propName )
	{