However, the signal "notify::source" is not listed in the playbin2's signals, mentioned in that page.
Is it a typo?
Or, is this signal inherited somehow?
If yes, then, how can I find the full list of signals and properties playbin2 has?
All GObjects emit / are supposed to emit a "notify" signal when one of
their properties changes. The property that changed will be used as the
signal 'detail', ie. the bit after '::', so in order to just catch when
the "source" property changes you would conect to the 'notify::source'
signal instead of the 'notify' signal.