# How to apply the “glow” effect to a rectangle with tcolorbox?

From page 195 of the tcolorbox manual, I can apply a "glow" effect on a circle:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tcolorbox}
\tcbuselibrary{skins}

\begin{document}
\begin{tcolorbox}[enhanced,width=2.5cm,
square,circular arc,
halign=center,valign=center,
colback=red!5!white,colframe=red!75!black,
frame style={circular glow={fill=red}} ]
tcolorbox
\end{tcolorbox}

\end{document}


I'm trying to set up a style with a "rectangular glow". When perusing the tikz manual, I found the following settings, which I guess are supposed to apply to a circular glow and therefore be somehow adaptable to a rectangular shape:

shadow scale=1.25, shadow xshift=0pt, shadow yshift=0pt,
fill=black, path fading={circle with fuzzy edge 15 percent},


Is there a way to adapt (presumably those settings) so that they work in a rectangle such as to generate a result like this one? (Just an example, not exactly the same colors.)

You might be interested in shadows.blur. There are many options how you could customize this, see texdoc pgfblur.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tcolorbox}
\tcbuselibrary{skins}

\begin{document}
\begin{tcolorbox}[enhanced,width=2.5cm,
square,%circular arc,
halign=center,valign=center,
colback=red!5!white,colframe=red!75!black,
]
tcolorbox
\end{tcolorbox}
\end{document}


Or

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tcolorbox}
\tcbuselibrary{skins}

\begin{document}
\begin{tcolorbox}[enhanced,width=2.5cm,
square,%circular arc,
halign=center,valign=center,
colback=red!5!white,colframe=red!75!black,
]
tcolorbox
\end{tcolorbox}
\end{document}


There are many options and many many ways to combine them.

The glowing effect can be achieved with Percusse's deleted answer.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tcolorbox}
\tcbuselibrary{skins}
\makeatletter
\pgfsyssoftpath@getcurrentpath{\pgfbs@input@path}%
\pgfbs@apply@canvas@transform%
\pgfsetfillcolor{#1}%
\pgfbs@usebbox{fill}%
\pgfbs@restorebb%
\makeatother
\begin{document}
\pagecolor{black}