@techee approved this pull request.
Yeah, it's much better this way - the callers of `document_show_tab()` don't have to care about the details of whether it should be on idle or not and the whole logic is in one place.
Also fixes the problem of the missing `document-activate` signal from what I tested. Just to clarify, `Notebook::switch-page` is fired also for a single tab, right? The documentation isn't completely clear about it but since `document-activate` is emitted in this case, it seems to be the case.