[Tex/LaTex] How to change color of ‘shadow’ around frametitle (Latex beamer)

Question

How do I change the blue shawdow around the frametitle to a different color?
Or rather even get rid of the shawdow

[Solution: I used the \setbeamercolor settings AFTER \begin{document}. Writing it before that solves the issue.]

Answer 1

With Warsaw you can modify the topshade colors.

\documentclass{beamer}%
\usetheme{Warsaw}
\setbeamercolor{frametitle right}{bg=cyan!90}
\setbeamercolor{structure}{fg=cyan!90}
\mode<presentation>
%\setbeamercolor{background canvas}{bg=yellow}
\definecolor{dgreen}{rgb}{0.,0.6,0.}
\makeatletter
\pgfdeclarehorizontalshading[frametitle.bg,frametitle right.bg]{beamer@frametitleshade}{\paperheight}{% Frametitle
    color(0pt)=(dgreen);
    color(\paperwidth)=(frametitle right.bg)}
\AtBeginDocument{
    \pgfdeclareverticalshading{beamer@topshade}{\paperwidth}{%
        color(4pt)=(blue);
        color(8pt)=(blue!50!bg)    
    }
}
\begin{document}

\section{A section}
\begin{frame}
  \frametitle{A section}
  \begin{itemize}
    \item Test test
    \begin{itemize}
        \item Test test
        \begin{itemize}
            \item Test test

        \end{itemize}
    \end{itemize}
  \end{itemize}

\end{frame}
\section{Another section}
\begin{frame}
  \frametitle{Another section}
  Yes!  Test test
\end{frame}
\section{Final section}
\begin{frame}
  \frametitle{Final section}
  No!  Test test
\end{frame}

\end{document}