Bug 139110 GUI enhancement to support create subquery more conveniently.
Description: GUI enhancement to support create subquery more conveniently. Steps to reproduce: Subquery means insert table/list inside another table/list item, and the inner table/list item doesn't has its own dataset binding. In latest build, if you want to creat a subquery structure, you have to use dataSetRow as binding expression for data items in inner table/list item. For example: 1. Insert a list, generate column data binding for it. 2. Add a group for the list. 3. Insert table to list group header which is used to display data rows in list group. Dont' bind table to dataset. 4. Insert a data to table detail row. 5. New a binding column for data, click to Open Expression Builder. The issue is that only "Availabel column bindings" is listed in Category but no "Available Data Sets". So I have to type dataSetRow[".."] by myself to generate correct subquery. For users, maybe they will mistakenly use "Available column bindings" which will generate expression like row._outer[".."] and get wrong result. So it is recommended to add "Available Data Sets" in Expression Builder for such case.
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
DesignElementHandle bindingHolder = getBindingHolder( elementHandle );
			if ( bindingHolder == holder )
			{
				return level;
			}
			if ( holder instanceof GroupHandle
					&& bindingHolder == holder.getContainer( ) )
			{
				return level;
			}
		}
		return -1;
	}
	/**
	 * Check if the given element is linked from a library or not.
	 * 
	 * @param handle
	 *            the handle of the element to check
	 * @return true if it is linked from a library ,or false if else;
	 * 
	 */
	public static boolean isLinked( DesignElementHandle handle )
	{
		if ( handle.getExtends( ) != null )
		{
			return handle.getExtends( ).getRoot( ) instanceof LibraryHandle;
		}
		return false;
	}
}