German quotation marks are broken in XeLaTeX

Question

Although I known nothing about German, I have to complie some German TeX documents. The German quotation marks "' or \grqq and "' or \grqq in my document are replaced by cmr font and the PDF file is not copyable near the quotation marks. A warning message says

font shape `OT1/TeXGyrePagella(0)/m/n' undefined, using `OT1/cmr/m/n' instead for symbol `glqq' on line 9.

The following is my minimal example:

% !TEX program = xelatex
% !Mode:: "TeX:UTF-8"
\documentclass[12pt]{article}
\usepackage[ngerman]{babel}
\usepackage{fontspec}
\defaultfontfeatures{Mapping=tex-text}
\setromanfont{TeXGyrePagella}
\begin{document}
These are German \glqq quotation marks\grqq.
\end{document} 

Answer 1

Never use babel with XeLaTeX. For internationalization support use polyglossia instead. Besides, in this case it's not even needed. You can enter the quotation marks either using ASCII symbols or direct UTF-8:

\documentclass{article}

\usepackage{fontspec}

\setmainfont[Ligatures = TeX]{TeX Gyre Pagella}

\begin{document}

<< >> ,, ``

« » „ “

\end{document}

polyglossia also has some babel shorthand support to ease the transition from babel.

Answer 2

Think you’d better use polyglossia instead of babel:

% !TEX program = xelatex
% !Mode:: "TeX:UTF-8"
\documentclass[12pt]{article}
\usepackage{polyglossia}
    \setmainlanguage[spelling=new,babelshorthands=true]{german}
\usepackage{fontspec}
\defaultfontfeatures{Mapping=tex-text}
\setromanfont{Times New Roman}
\newcommand\glqq{"`}
\newcommand\grqq{"'}
\begin{document}
Thess are German \glqq quotation marks\grqq.
Thess are German "`quotation marks"'.
\end{document}

(I changed the font …)

Answer 3

babel is not recommended if you use non-western scripts as it will confuse the font encodings but with german it will work fine with xelatex. You are not getting the quote because xunicode doesn't provide the necessary definitions. It is easy to add them. E.g.

\documentclass[12pt]{article}
\usepackage[ngerman]{babel}
\usepackage{fontspec}
\defaultfontfeatures{Mapping=tex-text}
\setromanfont{TeXGyrePagella}

\DeclareUTFcharacter[\UTFencname]{x201C}{\grqq}
\DeclareUTFcharacter[\UTFencname]{x201E}{\glqq}

\begin{document}
These are German \glqq quotation marks\grqq.
\end{document}

Also take a look at the package csquotes