+##### liblua #####
+website="http://www.lua.org/"
+PKG_CHECK_MODULES([LUA], [lua],
+ [LIBS="$LIBS $LUA_LIBS"
+ CFLAGS="$CFLAGS $LUA_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $LUA_CFLAGS"],
+ [missing=yes
+ AC_MSG_WARN([Missing liblua ($website)])])
+
+##### GTK+ 2.0 #####
+if test x$gtk = xyes
+then
+ website="http://www.gtk.org/"
+ PKG_CHECK_MODULES([GTK], [gtk+-2.0],
+ [LIBS="$LIBS $GTK_LIBS"
+ CFLAGS="$CFLAGS $GTK_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $GTK_CFLAGS"],
+ [missing=yes
+ AC_MSG_WARN([Missing GTK+-2.0 ($website)])])
+fi
+
+##### QT4 #####
+if test x$qt4 = xyes
+then
+ website="http://qt.nokia.com/"
+ PKG_CHECK_MODULES([QT], [QtGui],
+ [LIBS="$LIBS $QT_LIBS"
+ CFLAGS="$CFLAGS $QT_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $QT_CFLAGS"],
+ [missing=yes
+ AC_MSG_WARN([Missing QT ($website)])])
+fi
+
+if test x$missing = xyes
+then
+ AC_MSG_ERROR([You are missing some required libraries.])
+fi
+
+
+####
+AC_MSG_NOTICE([Checks for header files.])
+####