How to tackle complex overlays with columns, blocs, overprints and items?

Question

Though I had answers for mastering overlays with relative counts (cf here), I cannot manage to use it properly in complex situations with columns, blocs, overprints and items. The result is indescriptable. I have tried many tunings without success.

• Are pause counter as a tree or global to a frame?
• Am I obliged to calculate the number of slides per column and bloc and use static overlays numbering?

Here is my LyX code:

\documentclass[beamer]{beamerswitch}
\usetheme{metropolis}
\beamerdefaultoverlayspecification{<+->}

\begin{document}
\begin{frame}\frametitle{My title}
\beamerdefaultoverlayspecification{} %switch off for this slide

  \begin{columns}[t]
    \begin{column}{0.33\textwidth}
      \begin{block}<+(7)->{Middle-Left bloc - 2nd to appear} % 6 slides
    \begin{overprint}
      \only<+>{
        slide 1/2
      }
      \only<+-+(4)>{
        slide 2/2 :
        \begin{itemize}
          \item<+->  item 1
          \item<+->  item 2
          \item<+->  item 3
          \item<+->  item 4
        \end{itemize}
      \vspace*{2.6mm}
      }
    \end{overprint}
      \end{block}
    \end{column}

    \begin{column}{0.33\textwidth}
      \begin{block}<+->{Top-center bloc - 1st to appear} % 6 slides 
    \begin{overprint}
          \only<+>{
            slide 1
          }
          \only<+-+(3)>{
            slide 2
            \begin{itemize}
              \fontsize{7pt}{7.2}\selectfont
              \item<+-> item 1
              \item<+->  item 2
              \item<+->  item 3
            \end{itemize}
            \vspace*{2.6mm}
          }
          \only<+(3)>{
            slide 3
          }
        \end{overprint}
      \end{block}
      \begin{block}<+(25)->{Bottom-center bloc - 4th to appear} % 1 slides %\begin{block}[<+->]{Middle side}
        \begin{itemize}
          \fontsize{7pt}{7.2}\selectfont
          \item<+->  item 1
          \item<+->  item 2
          \item<+->  item 3
        \end{itemize}
        \vspace*{2.6mm}
      \end{block}
    \end{column}

    \begin{column}{0.33\textwidth}
      \begin{block}<+(13)->{Middle-right - 3rd to appear} % 12 slides % \begin{block}{\uncover<4->{Right side}}[<+(2)->]
    \begin{overprint}
      \only<+-+(2)>{
        slide 1 : 
        \begin{itemize}
          \fontsize{7pt}{7.2}\selectfont
          \item<+->  item 1
          \item<+->  item 2
        \end{itemize}
        \vspace*{2.6mm}
      }
      \only<+(2)-+(6)>{
        slide 2 :
        \begin{itemize}
          \fontsize{7pt}{8.4}\selectfont
          \item<+->  item 1
          \item<+->  item 2
          \item<+->  item 3
          \item<+->  item 4
        \end{itemize}
        \vspace*{2.6mm}
      }
      \only<+(6)-+(9)>{
        slide 3 :
        \begin{itemize}
          \fontsize{7pt}{7.2}\selectfont
          \item<+->  item 1
          \item<+->  item 2
          \item<+->  item 3
        \end{itemize}
        \vspace*{2.6mm}
      }
    \end{overprint}
      \end{block}
    \end{column}
  \end{columns}
\end{frame}
\end{document}

Please consider the comments where I specify the order othe blocks should appear. Here, I have calculated the number of slides per block to try to put the right overlay offset

block overlay offset = previous block overlay + previous block number of slides

Answer 1

It has been difficult, but by picking tricks at many places here, I could perform it by replacing columns by nodes - this is not conform to the OP but then I did not know about nodes.

Thought, overlay management with offset has been performed on trial and error, since I cannot figure out some rules to master it. If someone can put lights on this, he is welcome. Nevertheless, the following code behave as I want:

\documentclass[beamer]{beamerswitch}
\usetheme{metropolis}
\usepackage{tikz}
\usetikzlibrary{calc}
\usetikzlibrary{tikzmark}

\begin{document}
  \begin{frame}\frametitle{My title}
    \begin{tikzpicture}[remember picture,overlay]

      \node[anchor=north,text width=.3\textwidth] at ($(current page.north)+(0,-0.1\textheight)$) {
        \begin{block}{Top-center bloc - 1st to appear} % 6 slides 
        \begin{overprint}
          \only<+>{
            slide 1
          }
          \only<+-+(3)>{
            slide 2
            \begin{itemize}
              \fontsize{7pt}{7.2}\selectfont
              \item<+-> item 1
              \item<+->  item 2
              \item<+->  item 3
            \end{itemize}
            \vspace*{2.6mm}
          }
          \only<+(3)->{
            slide 3
          }
        \end{overprint}
        \end{block}
      };

      \node[anchor=west,text width=.3\textwidth] at (current page.west) {
        \begin{block}<+(3)->{Middle-Left bloc - 2nd to appear} % 6 slides
        \begin{overprint}
          \only<+(2)>{
            slide 1/2
          }
          \only<+(2)->{
            slide 2/2 :
            \begin{itemize}
              \item<+(2)->  item 1
              \item<+(2)->  item 2
              \item<+(2)->  item 3
              \item<+(2)->  item 4
            \end{itemize}
          \vspace*{2.6mm}
          }
        \end{overprint}
        \end{block}  
      };

      \node[anchor=east,text width=.3\textwidth] at (current page.east) {
        \begin{block}<+(2)->{Middle-right - 3rd to appear} % 12 slides
        \begin{overprint}
          \only<+-+(3)>{
            slide 1 : 
            \begin{itemize}
              \fontsize{7pt}{7.2}\selectfont
                  \item<+(1)->  item 1
              \item<+(1)->  item 2
            \end{itemize}
            \vspace*{2.6mm}
          }
          \only<+(3)-+(6)>{
            slide 2 :
            \begin{itemize}
              \fontsize{7pt}{8.4}\selectfont
                  \item<+(3)->  item 1
              \item<+(3)->  item 2
              \item<+(3)->  item 3
              \item<+(3)->  item 4
            \end{itemize}
            \vspace*{2.6mm}
          }
          \only<+(6)->{
            slide 3 :
            \begin{itemize}
              \fontsize{7pt}{7.2}\selectfont
              \item<+(6)->  item 1
              \item<+(6)->  item 2
              \item<+(6)->  item 3
            \end{itemize}
            \vspace*{2.6mm}
          }
        \end{overprint}
        \end{block}
      };

      \node[anchor=south,text width=.3\textwidth] at (current page.south) {
        \begin{block}<+(6)->{Bottom-center bloc - 4th to appear} % 1 slides
        \begin{itemize}
          \fontsize{7pt}{7.2}\selectfont
          \item<+(6)->  item 1
          \item<+(6)->  item 2
          \item<+(6)->  item 3
        \end{itemize}
        \vspace*{2.6mm}
      \end{block}
      };
    \end{tikzpicture}
  \end{frame}
\end{document}

Answer 2

Here is a LyX solution: source code:, code view in LyX snapshot, result: