```
\documentclass{beamer}

\usepackage{tikz}
\usepackage{tcolorbox}
\begin{document}

\begin{frame}{Frame Title}
	\begin{tikzpicture}[remember picture, overlay]
		% Position the tcolorbox in the top right corner
		\node[anchor=north east, xshift=-0.5cm, yshift=-0.3cm] at (current page.north east) {
			\begin{tcolorbox}[colback=blue!5, 
				colframe=blue!75!black, 
				fonttitle=\bfseries, 
				width=4.5cm, 
				fontupper=\tiny, boxsep=1pt,
				left=2pt,
				right=2pt,
				top=0pt,
				bottom=0pt]
				$u\leftarrow ${\sc Operation}$(Q)$\\
				For {each node $v$ in Adj$[u]$}
				\vspace{-0.1cm} 
				\begin{itemize}
					\setlength\itemsep{0.1em}
					\item[] \hspace{-2.8em} If {$v \in Q$ and } 
					\item[] \hspace{-1.8em} $key[v] \leftarrow $  // {\sc Comment}\;
					\item[] \hspace{-1.8em} $\pi[v] \leftarrow$\;
				\end{itemize}
			\end{tcolorbox}
		};
	\end{tikzpicture}
\end{frame}
\end{document}
```

I want to make the line around the box dashed. I tried adding borderline to tcolorbox's arguments but it complains it doesn't recognise it.