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
* 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 + "..."; 
		}
		return displayLabel;
	}
	/**
	 * Generates a clone copy of this element. When a report element is cloned,
	 * the basic principle is just copying the property value into the clone,
	 * the other things, like container references, child list references,
	 * listener references will not be cloned; that is, the clone is isolated
	 * from the design tree until it is added into a target design tree.