This is a tricky issue - currently left as a reminder. This is a remnant of an old API which used to be considered necessary in order to support operation across iframes - for example, in the UIOptions fat panel. It looks like this is still outstanding as FLUID-4530. It was discovered that we could operate a more economical system that just propagated the correct "expando" - this is operated inside fluid.createDomBinder in line 136 of FluidView.js - it "appears to work" but I wasn't completely confident that the old API attempt could be abandoned. Should we discover that everything is OK in testing on IE8 for this branch, especially in running the Fat Panel tests, I guess we can be sure that the FLUID-4530 API effort can be abandoned. We can't support the old method of simply updating the container entry in place because of conditions imposed by the new framework model on "referential transparency" - no material resolved via EL can ever be observed to change during the ginger process.