Cfxtrjtrk

I use a dialog-bubble style for some theorems, by using the code below, that works fine.

documentclass[a4paper,11pt,twoside]{book}

usepackage[a4paper,left=2.5cm,right=2.5cm,top=2.5cm,bottom=2.5cm]{geometry}

usepackage{amsthm}



usepackage{environ}



usepackage{tikz}

usetikzlibrary{shapes,snakes} % Για φάνσι κουτακια



theoremstyle{plain}

newtheorem{theo}{Sometheorem}[chapter]



tikzstyle{BoxDialog} = [draw=black, fill=white, very thick,

rectangle callout, rounded corners, densely dashed,callout relative pointer={(-0.4cm,-0.4cm)}, inner sep=4pt, inner ysep=8pt]

tikzstyle{TitlTheo} =[fill=white, text=black]



NewEnviron{dialogtheo}[1]{

                    begin{tikzpicture}

        node [BoxDialog] (boxtheo){%

            begin{minipage}{0.9textwidth}

            BODY

            end{minipage}

        };

        node[TitlTheo] at (boxtheo.north) {textbf{#1}};

        end{tikzpicture}

}



begin{document}



begin{dialogtheo}{title theorem}

begin{theo}

    theorem theorem theorem theorem theorem theorem theorem theorem theorem theorem

end{theo}

end{dialogtheo}



end{document}

But when I wrap center environment around the dialogtheo environment like this:

NewEnviron{dialogtheo}[1]{

        begin{center}

                        begin{tikzpicture}

        node [BoxDialog] (boxtheo){%

            begin{minipage}{0.9textwidth}

            BODY

            end{minipage}

        };

        node[TitlTheo] at (boxtheo.north) {textbf{#1}};

        end{tikzpicture}

        end{center}

}

I have this error report:

! LaTeX Error: Something's wrong--perhaps a
missing item.

This is the log-file.

What is the problem?

P.S.: If I ceep center environment, but I delete theo, everything is OK again.

If your goal is to center the dialog bubble, instead of using the center environment, you should try to use centering with a par at the end of the content of your environment:

NewEnviron{dialogtheo}[1]{

    centering

    begin{tikzpicture}

        node[BoxDialog] (boxtheo){

            begin{minipage}{0.9textwidth}

                BODY

            end{minipage}

        };

        node[TitlTheo] at (boxtheo.north) {textbf{#1}};

    end{tikzpicture}par

}

The par is important, else the bubble will not be centered at all.

If you try to place a theorem inside center environment, you will realize that it doesn't work.

Edit: I mean that the code:

begin{center}

    begin{theo}

    test

    end{theo}

end{center}

would result to a non-centered theorem.

So, my solution is a "hack" that just indenting your environment as much as needed:

documentclass[a4paper,11pt,twoside]{book}

usepackage[a4paper,left=2.5cm,right=2.5cm,top=2.5cm,bottom=2.5cm]{geometry}

usepackage{amsthm}

usepackage{lipsum}

usepackage{environ}



usepackage{tikz}

usetikzlibrary{shapes,decorations} % Για φάνσι κουτακια



theoremstyle{plain}

newtheorem{theo}{Sometheorem}[chapter]



tikzstyle{BoxDialog} = [draw=black, fill=white, very thick,

rectangle callout, rounded corners, densely dashed,callout relative pointer={(-0.4cm,-0.4cm)}, inner sep=4pt, inner ysep=8pt]

tikzstyle{TitlTheo} =[fill=white, text=black]



newsavebox{theobox}

newlength{theoidentlength}

NewEnviron{dialogtheo}[1]{

saveboxtheobox{hbox{

        begin{tikzpicture}

        node [BoxDialog] (boxtheo){%

            begin{minipage}{0.6textwidth}

            BODY

            end{minipage}

        };

        node[TitlTheo] at (boxtheo.north) {textbf{#1}};

        end{tikzpicture}}}

        setlengththeoidentlength{dimexpr(textwidth-wdtheobox)/2relax}

        noindenthspace*{theoidentlength}usebox{theobox}

}



begin{document}

lipsum[1]

begin{dialogtheo}{title theorem}



begin{theo}

    theorem theorem theorem theorem theorem theorem theorem theorem theorem theorem

end{theo}

end{dialogtheo}



end{document}

PS: My solution is just an alternative [that I think could be useful in many cases if centering fails], and just added as such (an alternative) approach.