dnl Checks for X11 and XShm
if test "x$mingw" != xyes; then
	AC_PATH_XTRA
	if test "x$no_x" = x; then
		HAVE_X=yes
		AC_CHECK_LIB(Xext, XShmQueryExtension,
			X_SHM_LIB=-lXext,
			HAVE_X=no,
			[ $X_LIBS -lX11 $X_EXTRA_LIBS ]
		)
	fi
	AC_SUBST(X_SHM_LIB)
fi
AC_SUBST(HAVE_X)

dnl Check for XFree86-VidMode support
AC_ARG_ENABLE(vidmode,
[  --disable-vidmode       do not use XFree86 VidMode extension],
	HAVE_VIDMODE=$enable_vidmode, HAVE_VIDMODE=auto)
if test "x$HAVE_VIDMODE" != xno; then
	save_CPPFLAGS="$CPPFLAGS"
	CPPFLAGS="$X_CFLAGS $CPPFLAGS"
	AC_CHECK_HEADER(X11/extensions/xf86vmode.h,
		dnl Make sure the library works
		[AC_CHECK_LIB(Xxf86vm, XF86VidModeSwitchToMode,
			AC_DEFINE(HAVE_VIDMODE, 1, [Define if you have the XFree86 VIDMODE extension])
			VIDMODE_LIBS="-lXxf86vm",,
			[$X_LIBS -lXext -lX11 $X_EXTRA_LIBS]
		)],
		[],
		[#include <X11/Xlib.h>]
	)
	CPPFLAGS="$save_CPPFLAGS"
fi
AC_SUBST(VIDMODE_LIBS)

dnl Check for DGA support
AC_ARG_ENABLE(dga,
[  --disable-dga           do not use XFree86 DGA extension],
HAVE_DGA=$enable_dga, HAVE_DGA=auto)
if test "x$HAVE_DGA" != xno; then
	save_CPPFLAGS="$CPPFLAGS"
	CPPFLAGS="$X_CFLAGS $CPPFLAGS"
	AC_CHECK_HEADER(X11/extensions/Xxf86dga.h,
		dnl Make sure the library works
		[AC_CHECK_LIB(Xxf86dga, XF86DGAQueryVersion,
			AC_DEFINE(HAVE_DGA, 1, [Define if you have the XFree86 DGA extension])
			DGA_LIBS="-lXxf86dga",,
			[$X_LIBS -lXext -lX11 $X_EXTRA_LIBS]
		)],
		[AC_CHECK_HEADER(X11/extensions/xf86dga.h,
			dnl Make sure the library works
			[AC_CHECK_LIB(Xxf86dga, XF86DGAQueryVersion,
				AC_DEFINE(HAVE_DGA, 1, [Define if you have the XFree86 DGA extension])
				AC_DEFINE(DGA_OLD_HEADERS, 1, [Define if DGA uses old headers])
				DGA_LIBS="-lXxf86dga",,
				[$X_LIBS -lXext -lX11 $X_EXTRA_LIBS]
			)],
			[],
			[#include <X11/Xlib.h>]
		)],
		[#include <X11/Xlib.h>]
	)
	CPPFLAGS="$save_CPPFLAGS"
fi
AC_SUBST(DGA_LIBS)