# Positioning TikZ pictures in beamer slide

I am trying to position a TikZ picture on a beamer slide but some nodes (well, not all?) get pushed to the right.

I have tried to add % wherever it seemed fitting as mentioned in Tikz figure in Beamer shifting way to the right of the frame, but that doesn't help. I have tried the adjustbox which only resize the nodes but doesn't move them to the right. My head hurts so maybe you could help since I probably have missed something. I can make things more or less work with the textblock environment but I think it's

Here is my MnotWE:

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{positioning}

\tikzstyle{block1} =[draw=black, fill=blue!40, rectangle, minimum height=0.25cm, minimum width=0.25cm, inner xsep=0.25cm, font=\bf\normalsize]
\tikzstyle{box1} =[draw=blue, fill=white, ultra thick, rectangle, inner ysep=0.25cm, inner xsep=0.25cm, minimum height=0.25cm]
\tikzstyle{fancytitle1} =[fill=black, rounded corners, text=white]

\begin{document}

\begin{frame}
\begin{tikzpicture}%
\node (preop) [block1] {blabla};
\node (op) [block1, right=.25cm of preop] {blabla};
\node (postop) [block1, right=.25cm of op] {blabla};
\node (posthp) [block1, right=.25cm of postop] {blabla};

\draw (preop) -- (op);
\draw (op) -- (postop);
\draw (postop) -- (posthp);

\node[box1, above= 2cm of preop] (box1) {%
\begin{minipage}{1\textwidth}%
\vspace{.5cm}%
\begin{itemize}%
\item tutu
\item tete
\end{itemize}%
\end{minipage}};

\node[fancytitle1, right=10pt] at (box1.north west) {Operation};

\end{tikzpicture}%
\end{frame}

\end{document}


1. I would like to have the minipage flush with the most left blabla node (preop); and both somewhere close to the left hand side of my slide.

2. Can we position a node relatively by giving separate measures for vertical and horizontal distance? I know there is such a thing as above left= 2 cm of XXX but what if I want 1cm above and 2cm left?

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The last sentence in the second paragraph is missing something... –  Caramdir Sep 30 '11 at 2:56

This is because of the left margin on the slide. If you wrap your tikzpicture in a \makebox[\textwidth][c]{...}, as explained in Martin Scharrer's answer to Center figure that is wider than \textwidth, it will be centered properly.
For your first additional question: Using above = 2cm of preop.west, anchor=west will align the Operation box with the left edge of the first blabla node.
For your second additional question: You can use above left = 1cm and 2cm of <node>.