Bug 119331 Library - name space terminology and behavior
During BIRT 2.0 library feature review meeting the following change was decided. - Change the term namespace to 'prefix' - By default use the library name as the prefix ( namespace ); the dialog to input prefix should be prompted only if hte auto generated prefix is not unique.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DNDUtil.java
* 
	 * @param targetObj
	 *            target elements
	 * @param transferData
	 *            transfer data,single object or array are permitted
	 * @param validateContainer
	 *            validate target's container can contain
	 * @return If target elements can't be dropped, return CONTAIN_NO.
	 *         <p>
	 *         If target elements can be dropped, return CONTAIN_THIS.
	 *         <p>
	 *         If target's container can be dropped, return CONTAIN_PARENT
	 */
	public static int handleValidateTargetCanContain( Object targetObj,
			Object transferData, boolean validateContainer )
	{
		if ( targetObj == null || transferData == null )
			return CONTAIN_NO;
		if ( transferData instanceof StructuredSelection )
		{
			return handleValidateTargetCanContain( targetObj,
					( (StructuredSelection) transferData ).toArray( ),
					validateContainer );
		}
		else if ( transferData instanceof Object[] )
		{
			Object[] array = (Object[]) transferData;
			if ( array.length == 1 )
			{
				return handleValidateTargetCanContain( targetObj,