How to stop nested itemizes being "again covered" in beamer-class

Question

I'm using \setbeamercovered with transparency for "still covered" and "again covered" to make the current points pop out more. But when using an itemize in an itemize the points of the inner itemize seem to inherit the transparency of the last item. How to avoid this?

Here's my minimal-code:

\documentclass{beamer}

\setbeamercovered{still covered={\opaqueness<1->{5}},again covered={\opaqueness<1->{60}}}

\begin{document}

\begin{frame}
  \frametitle{Quelle II}
  \begin{itemize}[<+>]
   \item Foo
   \item Bar
   \begin{itemize}
     \item Blah
     \item Blub
   \end{itemize}
 \end{itemize}
\end{frame}
\end{decument}

In this example Blah & Blub will never bee not transparent. Because they seem to 'inherit' the transparency from Bar.

Answer 1

The solution is described already here by using etoolbox.

So in your case do:

\documentclass{beamer}
\usepackage{etoolbox} % this is new

\setbeamercovered{still covered={\opaqueness<1->{5}},again covered={\opaqueness<1->{60}}}

% begining of the new definition
\makeatletter
\newcommand*\fix@beamer@close{%
  \ifnum\beamer@trivlistdepth>0
    \beamer@closeitem
  \fi
}
\newcommand*\fix@beamer@open{%
  \ifnum\beamer@trivlistdepth>0
    \gdef\beamer@closeitem{}%
  \fi
}
\BeforeBeginEnvironment{itemize}{\fix@beamer@close}
\AfterEndEnvironment{itemize}{\fix@beamer@open}
\makeatother
% end of the new definition

\begin{document}

\begin{frame}
  \frametitle{Quelle II}
  \begin{itemize}[<+>]
    \item Foo
    \item Bar
    \begin{itemize}
      \item Blah
      \item Blub
    \end{itemize}
  \end{itemize}
\end{frame}

\end{document}