In current design of entry sheet, there's no back and forward button. This may harm in case the user needs to go backward when he types the wrong password in a page contained by entry sheet. e.g. captive portal. And if the captive portal page is not designed very well ;( This needs some UI change so may not in time of shira but I think this is a missed part of entry sheet design.
It's up to the individual app to add the necessary input buttons (back, confirm, etc). The system does not impose any navigation on entry sheets by default. However the captive portal page might be a smart one to force system-level "back" to, for the reason cited. Casey and/or Arun, can you comment?
Hmm. Good catch. I think that in the captive portal scenario it would make sense to use the wrapper UI to provide navigation. I could see this useful for other window.open scenarios as well (like signing into facebook to important contacts). We can't expect that the proper in-page navigation is provided in every instance.
Closing old b2g "leak" bugs.