doc/html/qmake-common-projects.html#the-lib-template tells me that there is a DLL option that would build "a shared library (dll)".

Does this mean that this option is valid only on Windows?

If not, it is misleading to add the word "dll" since there are no DLLs on *nix and I presume on Mac too, and so I can file a bug asking for the wording to be changed.

Same goes for the plugin option there.