QProcess::startDetached cannot execute a file without .exe extension that requires elevated privileges

If you have an executable named foo.bar, you can start a process for it using QProcess::startDetached, but only if the executable doesn't require elevated priviledges. If an elevation is needed, Qt uses ShellExecuteEx instead of CreateProcess, but misses to pass classname "exefile", which causes the call to fail.
See https://blogs.msdn.microsoft.com/oldnewthing/20140210-00/ for extra info and solution.