Changing left margin in itemize environment of beamer class

Question

I can't figure out how to line up the symbols of an itemize environment in beamer with the left part of the main text. In other words, I would like to supress the left margin in beamer itemize lists.

It would be nice if the solution worked with any itemize label defined with

\setbeamertemplate{itemize item}[]

In order to make myself clearer, what beamer produces by default is something like:

Main text. Main text. Main text...
   * Item 1
   * Item 2
   * Item 3
   ....

and the desired result is

Main text. Main text. Main text...
* Item 1
* Item 2
* Item 3
....

Answer 1

The beamer class uses the same default lengths for the left margin like the base classes: \leftmargini, \leftmarginii etc. So you could adjust those lenghts. For instance:

\setlength{\leftmargini}{0pt}

You may insert any value instead of 0pt that fits for you.

Further requirements might require a redefiniton or patch of beamer's itemize environment. If you would like to have such complete control over the itemize environment, you could redefine it this way within your preamble:

\makeatletter
\renewcommand{\itemize}[1][]{%
  \beamer@ifempty{#1}{}{\def\beamer@defaultospec{#1}}%
  \ifnum \@itemdepth >2\relax\@toodeep\else
    \advance\@itemdepth\@ne
    \beamer@computepref\@itemdepth% sets \beameritemnestingprefix
    \usebeamerfont{itemize/enumerate \beameritemnestingprefix body}%
    \usebeamercolor[fg]{itemize/enumerate \beameritemnestingprefix body}%
    \usebeamertemplate{itemize/enumerate \beameritemnestingprefix body begin}%
    \list
      {\usebeamertemplate{itemize \beameritemnestingprefix item}}
      {\def\makelabel##1{%
          {%
            \hss\llap{{%
                \usebeamerfont*{itemize \beameritemnestingprefix item}%
                \usebeamercolor[fg]{itemize \beameritemnestingprefix item}##1}}%
          }%
        }%
      }
  \fi%
  \beamer@cramped%
  \raggedright%
  \beamer@firstlineitemizeunskip%
}
\makeatother

Until now it's just a copy of the original! But since it's in your preamble, you can modify it.

For example, replace \hss\llap by \rlap and the bullets will align with the text around:

...
      {\def\makelabel##1{%
          {%
            \rlap{{%
                \usebeamerfont*{itemize \beameritemnestingprefix item}%
...

Within this redefinition you could adjust the LaTeX list length macros. This requires to know how to work with the LaTeX list environment.

Answer 2

This seemed to work for me:

\settowidth{\leftmargini}{\usebeamertemplate{itemize item}}
\addtolength{\leftmargini}{\labelsep}