\setbeamertemplate{theorem begin}{
{
\usebeamerfont*{block title}
+ \usebeamercolor[fg]{block title}
\inserttheoremname
\inserttheoremnumber
\ifx\inserttheoremaddition\@empty\else\ (\inserttheoremaddition)\fi%
\inserttheorempunctuation
+ \usebeamercolor[fg]{block body}
}
\usebeamerfont*{block body}
}
% Don't break the line that "Proof." is on.
\setbeamertemplate{proof begin}{
\usebeamerfont*{block title}
+ \usebeamercolor[fg]{block title}
\insertproofname
\usebeamerfont*{block body}
+ \usebeamercolor[fg]{block body}
}
\setbeamertemplate{proof end}{}