+##### SDL_image #####
+website="http://www.libsdl.org/projects/SDL_image/"
+AC_CHECK_HEADERS([SDL/SDL_image.h],,
+ [missing=yes
+ echo "***** Missing SDL_image header ($website) *****"])
+AC_SEARCH_LIBS([IMG_Load], [SDL_image],,
+ [missing=yes
+ echo "***** Missing libSDL_image ($website) *****"])
+
+##### libvorbis #####
+website="http://www.xiph.org/downloads/"
+AC_CHECK_HEADERS([vorbis/codec.h vorbis/vorbisfile.h],,
+ [missing=yes
+ echo "***** Missing vorbis headers ($website) *****"])
+AC_SEARCH_LIBS([ov_open], [vorbisfile],,
+ [missing=yes
+ echo "***** Missing libvorbisfile ($website) *****"])
+
+##### liblua #####
+website="http://www.lua.org/"
+AC_CHECK_HEADERS([lua.h],,
+ [missing=yes
+ echo "***** Missing lua headers ($website) *****"])
+AC_SEARCH_LIBS([lua_load], [lua],,
+ [missing=yes
+ echo "***** Missing liblua ($website) *****"])
+
+if test x$gtk = xyes
+then
+ ##### GTK+ 2.0 #####
+ website="http://www.gtk.org/"
+ PKG_CHECK_MODULES([GTK], [gtk+-2.0],
+ [LIBS="$LIBS $GTK_LIBS"
+ CFLAGS="$CFLAGS $GTK_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $GTK_CFLAGS"],
+ [missing=yes
+ echo "***** Missing GTK+-2.0 ($website) *****"])
+fi
+
+if test x$qt4 = xyes
+then
+ ##### QT4 #####
+ website="http://qt.nokia.com/"
+ PKG_CHECK_MODULES([QT], [QtGui],
+ [LIBS="$LIBS $QT_LIBS"
+ CFLAGS="$CFLAGS $QT_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $QT_CFLAGS"],
+ [missing=yes
+ echo "***** Missing QT ($website) *****"])
+fi
+
+##### librt (optional) #####