bonanza
How to fix the line breaking problem in the citation footnote (without moving the footnote somewhere else)?
```
\documentclass{beamer}
\usepackage[sorting=none,backref=true,style=verbose,maxcitenames=2,maxbibnames=99,natbib=true]{biblatex}
\addbibresource{biblatex-examples.bib}
\begin{document}
\begin{frame}
\begin{columns}
\begin{column}{0.5\textwidth}
\centering
\includegraphics[width=0.9\textwidth,height=0.8\textheight]{example-image}
\end{column}%%
\begin{column}{0.5\textwidth}
\footfullcite{aksin} is used.
\end{column}%
\end{columns}
\end{frame}
\end{document}
```

Top Answer
samcarter
Normally the width of the footnote block is hard coded to `0.85\paperwidth`. You can slightly change the definition to use the current `\textwidth`:
```
\documentclass{beamer}
\usepackage[sorting=none,backref=true,style=verbose,maxcitenames=2,maxbibnames=99,natbib=true]{biblatex}
\addbibresource{biblatex-examples.bib}
\makeatletter
\renewcommand<>\@mpfootnotetext[1]{%
\global\setbox\@mpfootins\vbox{%
\unvbox\@mpfootins
\reset@font\footnotesize
\hsize\textwidth
\@parboxrestore
\protected@edef\@currentlabel
{\csname p@mpfootnote\endcsname\@thefnmark}%
\color@begingroup
\uncover#2{\@makefntext{%
\rule\z@\footnotesep\ignorespaces#1\@finalstrut\strutbox}}%
\color@endgroup}}
\makeatother
\begin{document}
\begin{frame}
\footfullcite{aksin} is used.
\end{frame}
\begin{frame}
\begin{columns}[onlytextwidth]
\begin{column}{0.5\textwidth}
\centering
\includegraphics[width=0.9\textwidth,height=0.8\textheight]{example-image-duck}
\end{column}%%
\begin{column}{0.5\textwidth}
\footfullcite{aksin} is used.
\end{column}%
\end{columns}
\end{frame}
\end{document}
```

----
# Update 2021:
This hack is no longer necessary, starting with v3.64, beamer now automatically adapts the width of the footnotes to the current column width.
Related commit: https://github.com/josephwright/beamer/commit/c91ed4218db8b9600bd1ab33edbd955bfb2ab75d