I would like to thank Boris Zbarsky for fixing bug 241694. As a result, both bug 15405 and bug 57906 were fixed as well and the stretching part of my bug, bug 228942 (not the event problem though, obviously).
Mozilla now has the same skills as Opera on the LiteraryMoose Ripped Canvas demo. Great!
Peter-Paul Koch should propably update his screen shot on viewport experiments (maybe some other things changed as well, don't think so, but it could be).