+ this allows to check for operating system families like e.g. @c wxOS_MAC and @c wxOS_UNIX.
+
+ Note that you can obtain more detailed informations about the current OS
+ version in use by checking the major and minor version numbers returned
+ by ::wxGetOsVersion() or by wxPlatformInfo::GetOSMajorVersion(),
+ wxPlatformInfo::GetOSMinorVersion().