# beamer | One Block displayed, the other covered

I want that when the first block is displayed, the second is gray, and vice versa.

\documentclass{beamer}
\usepackage[frenchb]{babel}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{epsfig,pslatex,colortbl}
\usepackage{graphics}
\usepackage{graphicx}%pour les includegraphics
\usepackage{array}
\usepackage{beamerthemesplit}
\usepackage{multicol}

\usetheme{PaloAlto}
\usecolortheme{orchid}
\begin{document}
\begin{frame}[t]{General formalization of haplotyping.}
\begin{block}{Inputs}
\begin{itemize}
\item A \alert{genotype matrix} $G$.
characters}.
\end{itemize}
\end{block}
\begin{block}{Outputs}
\begin{itemize}
\item A \alert{haplotype matrix} $H$.
\item Pairs of rows in $H$ \alert{explain} the rows of $G$.
\item The haplotypes in $H$ are \alert{biologically plausible}.
\end{itemize}
\end{block}
\end{frame}
\end{document}


When I use the code above, the two blocks appear together. But, I want the first block is displayed while the second is covered. Then, The first is covered and the second is displayed.

any help?

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## migrated from stackoverflow.comJul 3 '12 at 18:04

This question came from our site for professional and enthusiast programmers.

Do you mean that the first block appears first then when you press enter the second appears? –  Joseph Elcid Jul 2 '12 at 19:22
I mean that when the first appear, the second is covered and when I press enter the second appear and the first begin covered –  Nounou Biatrice Jul 2 '12 at 19:33
Then I'll ajust the solution I proposed to fit what you want –  Joseph Elcid Jul 2 '12 at 19:36
Welcome to TeX.sx! Your question was migrated here from Stack Overflow. Please register on this site, too, and make sure that both accounts are associated with each other (by using the same OpenID), otherwise you won't be able to comment on or accept answers or edit your question. –  Werner Jul 3 '12 at 18:09

You can use \uncover command for this.

\uncover<1>{Text only shown in first slide.}
\uncover<2-3>{Text only shown in second and third slide.}
\uncover<1,3>{Text only shown in first and third slide.}


The difference between appearance for hidden elements (gray or completely hidden) is a configuration option:

\setbeamercovered{invisible}
\setbeamercovered{transparent}


etc. See Beamer User Guide, Section 17.6.

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what I seek is \setbeamercovered{invisible} \setbeamercovered{transparent} Thanks ypnos –  Nounou Biatrice Jul 2 '12 at 19:59