Searching for text in *.* does not find it in my file filename.odt. Presumably, that is because *.odt is not in the list of extensions. When I add *.odt to the list, searching in *.* does find filename.odt.
In other words, *.* does not mean any file. It only means any file with a listed extension.
Is this correct? Is this what is intended? It is not how *.* is normally understood.