[XBL] Clarification: Locked attribute

[Marcos Caceres]

In section 2.5, can you please clarify a bit more how the locked 
attribute works. I find the example hard to follow (particularly "when 
the element is being processed"?). Does it remain locked after it has 
been processed? Can you maybe use a HTML example instead, the arbitrary 
UI language examples are sometimes hard to conceptualize.