Actually nevermind, we can't use Gecko's "pageshow" even, because of two reasons:
1) There's no XPCOM interface exposed by it, which would require changing wine-gecko and frankly, it complicates it for no reason (dispatching it is simple because we already handle the load event).
2) It's only dispatched on IE11 mode. We could conceivably add some compat mode to each event, but not sure if it's worth it at this point just for this one event…
I guess I'll keep the patch as-is but I'll push in the new fixes since they're quite serious.