Did you rebuild the RSL on 4.5? Mixing versions is not supported.
thanks for your reactivity.
Yes indeed i rebuilt the RSL on 4.5
Put a breakpoint in LayoutManager.as:doPhasedInstantiation and see if it
gets called more than 12 times. If so, there might be some slight change
that is now causing an invalidation loop.
i eventually had it work properly,
rebuilding from scaratch both .actionscript files (one for the RSL, the other for the main application).
Thanks for your answers