Htykuut

In the following LaTeX Beamer MWE, why is the spacing of the itemization so bad and why can it be fixed by adding a percentage sign after (... subitems)?

Most importantly: is there a reliable and elegant way to prevent this bad spacing in my presentations?

(I know that percentage signs somehow prevent parsing of line endings, but even starting the subitemization directly after (...subitems) doesn't have the same effect.)

documentclass{beamer}

begin{document}

    begin{frame}

    begin{columns}

        begin{column}{0.5textwidth}   

                begin{itemize}         

                    item A. (requires three sub-items)

                    begin{itemize}

                        item A.1

                        item A.2

                        item A.3

                    end{itemize}

                    item B

                end{itemize}

        end{column}

    end{columns}

end{frame}

end{document}

documentclass{beamer}

begin{document}

    begin{frame}

    begin{columns}

        begin{column}{0.5textwidth}   

                begin{itemize}         

                    item A. (requires three sub-items)%

                    begin{itemize}

                        item A.1

                        item A.2

                        item A.3

                    end{itemize}

                    item B

                end{itemize}

        end{column}

    end{columns}

end{frame}

end{document}

The definition of itemize in beamer is buggy. The problem is that is sets a color before the list, and color commands inserts whatsits and this has the effect that the space suddenly matters. beamer should at least add an unskip before the color:

documentclass{beamer}

makeatletter



renewcommand{itemize}[1]{%

  ifhmodeunskipfi %<<< or unskip par

  ifblank{#1}{}{defbeamer@defaultospec{#1}}%

  ifnum @itemdepth >2relax@toodeepelse

    advance@itemdepth@ne

    beamer@computepref@itemdepth% sets beameritemnestingprefix

    usebeamerfont{itemize/enumerate beameritemnestingprefix body}%

    usebeamercolor[fg]{itemize/enumerate beameritemnestingprefix body}% problem

    usebeamertemplate{itemize/enumerate beameritemnestingprefix body begin}%

    list

      {usebeamertemplate{itemize beameritemnestingprefix item}}

      {defmakelabel##1{%

          {%

            hssllap{{%

                usebeamerfont*{itemize beameritemnestingprefix item}%

                usebeamercolor[fg]{itemize beameritemnestingprefix item}##1}}%

          }%

        }%

      }

  fi%

  beamer@cramped%

  raggedright%

  beamer@firstlineitemizeunskip%

}



begin{document}

    begin{frame}

        begin{minipage}{0.5textwidth}

                begin{itemize}

                    item A. (requires three sub-items)                   

                    begin{itemize}

                        item A.1

                        item A.2

                        item A.3

                    end{itemize}

                    item B

                end{itemize}

        end{minipage}

end{frame}

end{document}

Thanks, I found another reason for not relying on indentation but rather on spacing out the input. ;-)

Yes, itemize in beamer has a small bug, but it becomes irrelevant if you type in like the left column below.

documentclass{beamer}

begin{document}



begin{frame}



begin{columns}

begin{column}{0.5textwidth}   



begin{itemize} 

item A. (requires three sub-items)



begin{itemize}

item A.1

item A.2

item A.3

end{itemize}



item B



end{itemize}

end{column}



begin{column}{0.5textwidth}   



begin{itemize} 

item A. (requires three sub-items)

begin{itemize}

item A.1

item A.2

item A.3

end{itemize}



item B



end{itemize}

end{column}



end{columns}



end{frame}



end{document}