How to disable color gradient between block title and block body in Beamer?

Question

I'm using the "Warsaw theme" in my beamer slides, so how could I

1. Disable color gradient between block title and block body;
2. Disable the block's shade;
3. I don't want to use the "Berkeley theme" which has no a block with "Rounded Corner Rectangle".

thanks.

Answer 1

Warsaw internally uses beamerboxesrounded which applies the bmb@transition shading to add color between the title and the body parts of blocks. Here's the original definition (found in the file beamerbaseboxes.sty):

\pgfdeclareverticalshading[lower.bg,upper.bg]{bmb@transition}{200cm}{%
  color(0pt)=(lower.bg); color(2pt)=(lower.bg); color(4pt)=(upper.bg)}

Change that definition to suppress the transition effect.

To suppress the shading, redefine the blocks template using

\setbeamertemplate{blocks}[rounded][shadow=false] 

The complete code:

\documentclass{beamer}
\usetheme{Warsaw}

\setbeamertemplate{blocks}[rounded][shadow=false]
\makeatletter
\pgfdeclareverticalshading[lower.bg,upper.bg]{bmb@transition}{200cm}{%
  color(0pt)=(upper.bg); color(2pt)=(upper.bg); color(4pt)=(upper.bg)}
\makeatother

\begin{document}
\begin{frame}{A frame}
\begin{block}{A block}
    Some text
\end{block}
\end{frame}
\end{document}

Answer 2

If you use the tcolorbox inner theme, you can switch the shadow and shading between the title and the body off like this:

\documentclass{beamer}
\usetheme{Warsaw}

\useinnertheme[shaded=false,shadow=false]{tcolorbox}

\begin{document}
\begin{frame}
  \begin{block}{Title}
  Block stuff.
  \end{block}
\end{frame}
\end{document}