Colors in underbrace and overbrace - strange behaviour

Question

There is a strange inconsistency between \overbrace and \underbrace when one wishes to have the associated text (above or below) in a different color.

\underbrace behaves as expected and \overbrace does not -- both the text below the brace and above are changed by the color command, not just the raised text. To try to fix a \color{black} is required inside the {} for the lower text. However, the brace remains red. Is this an error in xcolor?

\documentclass[a4paper,12pt,oneside,pdftex]{article}

\usepackage{amsmath}
\usepackage[dvipsnames]{xcolor}

\begin{document}

$$\underbrace{x}_{\color{red} \sin t} \overbrace{x}^{\color{red} \sin t} \quad \overbrace{\color{black}x}^{\color{red} \sin t} $$

\end{document}

Answer 1

You can either use \textcolor instead of \color or enclose the whole superscript in an extra set of {}:

\documentclass[a4paper,12pt,oneside,pdftex]{article}

\usepackage{amsmath}
\usepackage[dvipsnames]{xcolor}

\begin{document}

\[\underbrace{x}_{\color{red} \sin t} \overbrace{x}^{\textcolor{red}{\sin t}} \quad \overbrace{x}^{{\color{red} \sin t}} \]

\end{document}