Keep a fragmented tikz image at the same place on a beamer slide [duplicate]

Possible Duplicate:
How can I fix jumping TikZ pictures in beamer?

I am putting together a series of slides using beamer, and I'm using tike to do most of the figures. On one particular slide, I need to make nodes appear, then some more nodes, then edges between them. The code looks like this:

\begin{tikzpicture}[>=latex,text height=1.5ex,text depth=0.25ex]
\draw[help lines] (0,0) grid (10.5,7.5);
\tikzstyle{every node}=[draw,minimum size = .4cm,circle,draw=none,fill=red!30!white]
\tikzstyle{every path}=[solid,thick]
%% First species
\draw (3.7,2.2) node (a) {};
\draw (9.6,1.4) node (b) {};
\draw (6.6,6.6) node (c) {};
%% Second species
\draw <2-> (0.4,4.0) node [fill=blue!30!white] (d) {};
\draw <2-> (4.4,3.6) node [fill=blue!30!white] (e) {};
\draw <2-> (8.0,3.4) node [fill=blue!30!white] (f) {};
%% Third species
\draw <3-> (1.3,5.2) node [fill=green!30!white] (g) {};
\draw <3-> (4.5,6.4) node [fill=green!30!white] (h) {};
\draw <3-> (3.8,0.45) node [fill=green!30!white] (i) {};
%% Arrows
\path <4> [<->] (g) edge [bend right] (d);
\path <4> [<->] (g) edge [bend left] (e);
\path <4> [<->] (h) edge [bend left] (c);
\path <4> [<->] (e) edge [bend left] (a);
\path <4> [<->] (i) edge [bend left] (a);
\path <4> [<->] (i) edge [bend right] (f);
\path <4> [<->] (b) edge [bend right] (f);
\path <4> [<->] (e) edge [bend left] (f);
\path <4> [<->] (e) edge [bend right] (h);
\path <4> [<->] (f) edge [bend right] (c);
\end{tikzpicture}


My problem is that, when I remove the help lines, the figure changes positions on the slide between each transition, which is really not what I expected. I found a quick-and-dirty way to fix the problem with draw=none for the help line, but if anyone here ran into the same problem, I'd like to know a way towards a solution.

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marked as duplicate by Loop Space, percusse, Jake, egreg, Torbjørn T.Jun 28 '12 at 15:18

Please make sure to post complete compilable examples, starting from \documentclass. That makes it easier for others to try out your code. – Jake Jun 26 '12 at 14:27

\path[use as bounding box] (0,0) rectangle(10.5,7.5);