\usepackage{etex}
\usepackage{pgfpages}

\usepackage{color}

\usepackage{tikz}
\usetikzlibrary{shapes}
\usetikzlibrary{backgrounds}

% beamer mode
\mode<beamer>{
 \usetheme{Warsaw}
}

% transparency mode
\mode<trans>{
 \usetheme{Warsaw}
}

% handout mode
\mode<handout>{
 \usetheme{default}
 \setbeamercolor{background canvas}{bg=black!5}
 \pgfpagesuselayout{4 on 1}[letterpaper,landscape,border shrink=2.5mm]
}

\newcommand{\return}[2]{\hyperlink{#1}{\beamerreturnbutton{#2}}}
\newcommand{\goto}[2]{\hyperlink{#1}{\beamergotobutton{#2}}}
\newcommand{\skipto}[2]{\hyperlink{#1}{\beamerskipbutton{#2}}}