In an search field with the incremental attribute, onsearch will fire when pressing backspace in an empty search field. This seems unintentional, since the text in the search field hasn't actually changed.
I can only reproduce this with TOT, not with shipping Safari.
<rdar://problem/5215963>
dispatchEditableContentChangedEvents is called when any editing command is applied or unapplied, but that doesn't actually mean that the editable content has changed. I guess we need to rethink this event.