Color of vertical shadow in frametitle, beamer, warsaw

Question

I know that's its a common topic, but still I don't get it to work. I want a different background color (due to corporate design) and shadows which fade to that new color.

I have checked several threads, where the shadow is removed (that's not what i want) or where the shadow color is changed manually.

Latex beamer block shadow fades to white and not to the background color

-> The solution has no effect on the title-shadow

How to add a transparent shadow to a block in beamer?

-> I changed the beamerbaseboxes.sty, but it had no effect (I refreshed the FNDB and updated the formats after replacing the file)

My minimal example:

\documentclass{beamer}
\usetheme{Warsaw}
\setbeamercolor{background canvas}{bg=yellow}

\begin{document}
   \begin{frame}{Nice Title}
       Stupid Content
   \end{frame}
\end{document}

The result is (I added arrows to emphasize the shadow):

I expect the vertical shadow to start from black and end at yellow, like the background is.

Best regards, karl.ranseier

Answer 1

This bug was fixed in https://github.com/josephwright/beamer/commit/c7051f7003834fb06e40e97288de03f1364163f1 and is included in beamer v3.51 or v3.60 and newer

(the new transparent shadows had some problems, so they were temporarily disabled again for beamer v3.52-v3.59)

\documentclass{beamer}
\usetheme{Warsaw}
\setbeamercolor{background canvas}{bg=yellow}
\AtBeginDocument{
    \pgfdeclareverticalshading{beamer@topshade}{\paperwidth}{%
        color(0pt)=(yellow);
        color(4pt)=(black!50!bg)

    }
}
\begin{document}
   \begin{frame}{Nice Title}
       Stupid Content
   \end{frame}
\end{document}