Redefine beamer's blocks

I'm trying to redefine beamer's blocks to obtain something like this (upper block) :

I've found 3 sites (with codes and pictures) which may help, but I'm unable to reach this goal on my own.

Here's the sites :

Thanks for any help.

• Well, we should follow three links in order to assemble a solution? ;-) – user31729 Sep 21 '14 at 10:03
• Please add a full minimal working example so that people can see what you have tried so far and how close you have come to a solution (but don't add unnecessary code). This code should start with \documentclass and end with \end{document} and it should compile. Doing this makes it much easier for people to help you - and much more likely that they will:) As it is we have no idea what beamer styles etc you are using and so we'd have to waste a lot time starting from scratch – Andrew Sep 21 '14 at 10:09

This is a tcolorbox based implementation.

\documentclass{beamer}

\usepackage{tikz,tcolorbox}
\usetikzlibrary{shapes,calc}
\tcbuselibrary{skins}
\definecolor{myblue}{rgb}{0.15,0.15,0.53}

\makeatletter

\newtcbox{\titlebox}{
enhanced,
overlay={
\draw[myblue,fill=myblue](frame.south east)--+(0,.2)to[bend right]+(.2,-0)--cycle;},
colback=myblue,
top=-1pt,bottom=-2pt,left=2pt,right=2pt,
boxrule=1pt,
colframe=myblue,
sharp corners=south,
colupper=white,
fontupper=\bfseries
}

\newtcolorbox{myblock}[1][]{
enhanced,
left=2pt,
right=2pt,
colframe=myblue,
boxrule=1pt,
colback=blue!10,
overlay={
\def\myblock@tempa{#1}
\ifx\myblock@tempa\@empty
\else
\draw[myblue,fill=myblue]($(frame.north west)+(.2pt,-.2pt)$)--+(.1,0)to[bend right]+(-0,-.1)--cycle;
\node [
anchor=south west,
inner sep=0pt,
outer sep=0pt
]at(frame.north west){\titlebox{#1}};
\fi
},
}
\makeatother
\begin{document}
\begin{frame}
\begin{myblock}[Corollary]
\textit{If $_{\chi PP}(M)=2$ a haplotype matrix M we can find an optimal pp-partition in polynomial time}
\end{myblock}

\begin{myblock}
this block has no title
\end{myblock}
\end{frame}

\end{document}


The fancy stuff (rounded corners etc. is done with TikZ and is conditionally excluded if the box has no title.