How to keep highlighted the mini frames of already discussed slides?

Question

I would like for the dots in the mini frame of my beamer presentation to be full circles and remain highlighted once I already discussed the corresponding slide. Let me make this clearer: when you are showing a slide of your presentation, the corresponding dot in the mini frame on top highlights in order to make the audience follow you up. I would like, once I change slide, for the already coloured dots to remain coloured in black. Like in a loading bar. Is that possible to achieve in a simple way? I have, unfortunatly, no time to create my own theme :) Thanks a lot in advance to anyone who will have the time and patient to answer.

\documentclass{beamer}

% Stile for Beamer
\usetheme{Singapore}
\usecolortheme{rose}
\usepackage[english]{babel}
\useoutertheme[]{miniframes} 

\begin{document}

\section{hello}
\subsection{}
\begin{frame}
hello
\end{frame}

\begin{frame}
hello
\end{frame}

\end{document}

Answer 1

This seems to be a variation of part of the code I provided in this answer to Beamer: how to change the mini frames from circles to rectangles. Here's is the required code (change the color specifications according to the color schema of your theme, if required):

\documentclass[compress]{beamer}
\usetheme{Singapore}
\usecolortheme{rose}
\usepackage[english]{babel}
\useoutertheme{miniframes}

\definecolor{dark-gray}{gray}{0.10} %color for the navigation squares

\makeatletter

\def\slideentry#1#2#3#4#5#6{%
  %section number, subsection number, slide number, first/last frame, page number, part number
  \ifnum#6=\c@part\ifnum#2>0\ifnum#3>0%
    \ifbeamer@compress%
      \advance\beamer@xpos by1\relax%
    \else%
      \beamer@xpos=#3\relax%
      \beamer@ypos=#2\relax%
    \fi%
  \hbox to 2pt{%
    \beamer@tempdim=-\beamer@vboxoffset%
    \advance\beamer@tempdim by-\beamer@boxsize%
    \multiply\beamer@tempdim by\beamer@ypos%
    \advance\beamer@tempdim by -.05cm%
    \raise\beamer@tempdim\hbox{%
      \beamer@tempdim=\beamer@boxsize%
      \multiply\beamer@tempdim by\beamer@xpos%
      \advance\beamer@tempdim by -\beamer@boxsize%
      \advance\beamer@tempdim by 1pt%
      \kern\beamer@tempdim
      \global\beamer@section@min@dim\beamer@tempdim
      \hbox{\beamer@link(#4){%
          \usebeamerfont{mini frame}%
          \ifnum\c@section>#1%
            \color{dark-gray}%
          \else%
            \ifnum\c@section=#1%
              \ifnum\c@subsection>#2%
                \color{dark-gray}%
              \else%
                \ifnum\c@subsection=#2%
                  \ifnum\c@subsectionslide>#3%
                    \color{dark-gray}%
                  \else%
                    \color{dark-gray}%
                  \fi%
                \else%
                  \color{white}%
                \fi%
              \fi%
            \else%
              \color{white}%
            \fi%
          \fi%
          \usebeamertemplate{mini frame}%
        }}}\hskip-10cm plus 1fil%
  }\fi\fi%
  \else%
  \fakeslideentry{#1}{#2}{#3}{#4}{#5}{#6}%
  \fi\ignorespaces
  }

\makeatother

\begin{document}

        \section{Introduction}
            \subsection{Introduction}   
                \begin{frame}{Frame}
                    1
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    2
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    3
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    4
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    5
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    6
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    7
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    8
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    9
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    10
                \end{frame}                 

        \section{Introduction}
            \subsection{Introduction}   
                \begin{frame}{Frame}
                    11
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    12
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    13
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    14
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    15
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    16
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    17
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    18
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    19
                \end{frame}

            \subsection{Introduction}   
                \begin{frame}{Frame}
                    20
                \end{frame}

\end{document}

An animation showing the result with the desired scheme for the mini frames: