Alignment on title page different for options t and c

[jolars]

Options t and c change the alignment of the title page as well as the frames. Is this intentional?

\documentclass[c]{beamer}

\usepackage{xcolor}
\usepackage[grid, gridunit=mm, gridcolor=black!40, subgridcolor=black!20]{eso-pic}

\title{Title}

\begin{document}

\maketitle

\end{document}

Only changing \documentclass[t]{beamer} gives me:

[samcarter]

I don't know if that's intentional, but when I write a theme in which I want to make sure that the title page always looks the same, then I usually add a minipage of fixed height to the title page template (or position the elements relative to the page).

[jolars]

Yes, I remember you giving that suggestion for moloch, but it seems like it is not removing this effect completely, or I might be doing something wrong.

\documentclass[c]{beamer}

\setbeamertemplate{title page}{
  \begin{minipage}[b][\textheight]{\textwidth}
    \null\vfill%
    \usebeamertemplate{title}
    \vfill\null%
  \end{minipage}%
}

\usepackage{xcolor}
\usepackage[grid, gridunit=mm, gridcolor=black!40, subgridcolor=black!20]{eso-pic}

\title{Title}

\begin{document}

\maketitle

\end{document}

With t I see this:

[samcarter]

The remaining difference is the different topskip between top and centred frames. With the same topskip:

\documentclass[c]{beamer}

\setbeamertemplate{title page}{
  \begin{minipage}[b][\textheight]{\textwidth}
    \null\vfill%
    \usebeamertemplate{title}
    \vfill\null%
  \end{minipage}%
}

\makeatletter
\define@key{beamerframe}{c}[true]{% centered
  \beamer@frametopskip=0pt plus 1fill\relax%
  \beamer@framebottomskip=0pt plus 1.5fill\relax%
  \beamer@frametopskipautobreak=0pt plus .4\paperheight\relax%
  \beamer@framebottomskipautobreak=0pt plus .6\paperheight\relax%
}
\define@key{beamerframe}{t}[true]{% top
  \beamer@frametopskip=0pt plus .5\paperheight\relax%
  \beamer@framebottomskip=0pt plus 1fill\relax%
  \beamer@frametopskipautobreak=\beamer@frametopskip\relax%
  \beamer@framebottomskipautobreak=\beamer@framebottomskip\relax%
}
\makeatother

\usepackage{xcolor}
\usepackage[grid, gridunit=mm, gridcolor=black!40, subgridcolor=black!20]{eso-pic}

\title{Title}

\begin{document}

\begin{frame}[t]
\maketitle
\end{frame}

\begin{frame}[c]
\maketitle
\end{frame}

\end{document}

[jolars]

Thanks! But I guess it's not straightforward to have this apply only to the title page (without too much hacking).