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
* 
	 * @return the name of this element for display label.
	 */
	protected String getNameForDisplayLabel( )
	{
		return getName( );
	}
	/**
	 * All descriptive text should be "elided" to a length of 30 characters. To
	 * elide the text, find the first white-space before the limit, truncate the
	 * string after that point, and append three dots "...".
	 * <p>
	 * 
	 * @param displayLabel
	 *            the display label to be elided.
	 * @return the elided display label.
	 */
	protected String limitStringLength( String displayLabel )
	{
		if ( displayLabel == null )
			return null;
		if ( displayLabel.length( ) > MAX_DISPLAY_LABEL_LEN )
		{
			displayLabel = displayLabel.substring( 0, MAX_DISPLAY_LABEL_LEN );
			int pos = displayLabel.lastIndexOf( " " ); 
			if ( pos != -1 )
			{
				displayLabel = displayLabel.substring( 0, pos );
			}
			return displayLabel + "...";