Ex: https://github.com/codebrainz/geany/commit/807f6208dff8807617aeaeebe6a54d13a24748ce#diff-c623d8f0d3d09ca711551eee2ea7f132R37

Keep in mind it's re-worded from what I believe to be the better way (using forward-decl everywhere you can get away with it), to just mentioning the one case where it's strictly required :)