Ext JS 4 supports deprecated mutation events only.
I've been working for few days with mutation events, since there was no alternatives in Ext JS 4, but as I was afraid so, mutation events are not well supported or there is no common behaviour in today's browsers (FF, Chrome, IE, ...). On the other hand, mutation observers support seems to be good enough on FF, Safari and Chrome to rely on it (no support on IE9 and IE10).
Is mutation observers support planned in the roadmap of Ext JS 4?
If yes, what is the expected date of delivery/milestone?
If no, shall the answer to this question be yes as soon as possible? :-)
I think at this stage it would be out of scope for Ext JS 4. Since there isn't IE support (especially since we support IE6) then we still have to do old school stuff.