SF #859810, typo in doc

Doc/mac/libmacos.tex

@@ -148,7 +148,7 @@ differences.
 \end{funcdesc}
 
 \begin{funcdesc}{WMAvailable}{}
-Checks wether the current process has access to the window manager.
+Checks whether the current process has access to the window manager.
 The method will return \code{False} if the window manager is not available,
 for instance when running on Mac OS X Server or when logged in via ssh,
 or when the current interpreter is not running from a fullblown application