diff --git a/configure b/configure
index 1eb43eb..0a37270 100755
--- a/configure
+++ b/configure
@@ -649,17 +649,17 @@ LIBOBJS
 ENABLE_COMPLETION_FALSE
 ENABLE_COMPLETION_TRUE
 SDL2_CONFIG
-WHICH
 WISH
 COMPLETION_DIR
 PKG_CONFIG
-FILE
+XDG_OPEN
 MONTAGE
+WHICH
+FILE
 DIRNAME
 CHMOD
 GIT
 OPENSSL
-XDG_OPEN
 MAN
 ZIP
 UNZIP
@@ -1442,7 +1442,7 @@ Optional Features:
   --disable-dependency-tracking
                           speeds up one-time build
   --disable-rpath         do not hardcode runtime library paths
-  --enable-gui            enable GUI default: 'enabled'
+  --disable-gui           disable GUI default: 'enabled'
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -7320,9 +7320,9 @@ DYNAMIC_MEMORY_SIZE=$DYNAMIC_MEMORY_SIZE
 # Check whether --enable-gui was given.
 if test ${enable_gui+y}
 then :
-  enableval=$enable_gui; GUI=yes
+  enableval=$enable_gui; GUI=$enableval
 else case e in #(
-  e) GUI=no ;;
+  e) GUI=yes ;;
 esac
 fi
 
@@ -7609,64 +7609,6 @@ if test -z "${AWK}"; then
    exit 1
 fi
 
-for ac_prog in xdg-open open
-do
-  # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_path_XDG_OPEN+y}
-then :
-  printf %s "(cached) " >&6
-else case e in #(
-  e) case $XDG_OPEN in
-  [\\/]* | ?:[\\/]*)
-  ac_cv_path_XDG_OPEN="$XDG_OPEN" # Let the user override the test with a path.
-  ;;
-  *)
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_path_XDG_OPEN="$as_dir$ac_word$ac_exec_ext"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-  ;;
-esac ;;
-esac
-fi
-XDG_OPEN=$ac_cv_path_XDG_OPEN
-if test -n "$XDG_OPEN"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $XDG_OPEN" >&5
-printf "%s\n" "$XDG_OPEN" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-  test -n "$XDG_OPEN" && break
-done
-test -n "$XDG_OPEN" || XDG_OPEN="no"
-
-
-if test "$XDG_OPEN" = "no" ; then
-   as_fn_error $? "Can not find xdg-open." "$LINENO" 5
-   exit 1;
-fi
-
 for ac_prog in openssl
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.
@@ -7899,64 +7841,6 @@ if test "$DIRNAME" = "no" ; then
    exit 1;
 fi
 
-for ac_prog in montage montage-im6.q16 montage-im6
-do
-  # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_path_MONTAGE+y}
-then :
-  printf %s "(cached) " >&6
-else case e in #(
-  e) case $MONTAGE in
-  [\\/]* | ?:[\\/]*)
-  ac_cv_path_MONTAGE="$MONTAGE" # Let the user override the test with a path.
-  ;;
-  *)
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_path_MONTAGE="$as_dir$ac_word$ac_exec_ext"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-  ;;
-esac ;;
-esac
-fi
-MONTAGE=$ac_cv_path_MONTAGE
-if test -n "$MONTAGE"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $MONTAGE" >&5
-printf "%s\n" "$MONTAGE" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-  test -n "$MONTAGE" && break
-done
-test -n "$MONTAGE" || MONTAGE="no"
-
-
-if test "$MONTAGE" = "no" ; then
-   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: Can not find imagemagick 'montage' executable." >&5
-printf "%s\n" "$as_me: WARNING: Can not find imagemagick 'montage' executable." >&2;}
-fi
-
 for ac_prog in file
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.
@@ -8015,123 +7899,6 @@ if test "$FILE" = "no" ; then
    exit 1;
 fi
 
-for ac_prog in pkg-config
-do
-  # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_path_PKG_CONFIG+y}
-then :
-  printf %s "(cached) " >&6
-else case e in #(
-  e) case $PKG_CONFIG in
-  [\\/]* | ?:[\\/]*)
-  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
-  ;;
-  *)
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_path_PKG_CONFIG="$as_dir$ac_word$ac_exec_ext"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-  ;;
-esac ;;
-esac
-fi
-PKG_CONFIG=$ac_cv_path_PKG_CONFIG
-if test -n "$PKG_CONFIG"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
-printf "%s\n" "$PKG_CONFIG" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-  test -n "$PKG_CONFIG" && break
-done
-test -n "$PKG_CONFIG" || PKG_CONFIG="no"
-
-
-COMPLETION_DIR=""
-if test "$PKG_CONFIG" != "no" ; then
-   COMPLETION_DIR=`pkg-config --variable=completionsdir bash-completion`
-
-fi
-
-for ac_prog in wish
-do
-  # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-printf %s "checking for $ac_word... " >&6; }
-if test ${ac_cv_path_WISH+y}
-then :
-  printf %s "(cached) " >&6
-else case e in #(
-  e) case $WISH in
-  [\\/]* | ?:[\\/]*)
-  ac_cv_path_WISH="$WISH" # Let the user override the test with a path.
-  ;;
-  *)
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  case $as_dir in #(((
-    '') as_dir=./ ;;
-    */) ;;
-    *) as_dir=$as_dir/ ;;
-  esac
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
-    ac_cv_path_WISH="$as_dir$ac_word$ac_exec_ext"
-    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-  ;;
-esac ;;
-esac
-fi
-WISH=$ac_cv_path_WISH
-if test -n "$WISH"; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $WISH" >&5
-printf "%s\n" "$WISH" >&6; }
-else
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-fi
-
-
-  test -n "$WISH" && break
-done
-test -n "$WISH" || WISH="no"
-
-
-if test "$WISH" = "no" ; then
-   as_fn_error $? "Can not find TK interpreter executable." "$LINENO" 5
-   exit 1;
-fi
-
 for ac_prog in which
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.
@@ -8190,7 +7957,243 @@ if test "$WHICH" = "no" ; then
    exit 1;
 fi
 
-for ac_prog in sdl2-config
+
+if test "$GUI" = "yes" ; then
+
+   for ac_prog in montage montage-im6.q16 montage-im6
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+printf %s "checking for $ac_word... " >&6; }
+if test ${ac_cv_path_MONTAGE+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) case $MONTAGE in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_MONTAGE="$MONTAGE" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  case $as_dir in #(((
+    '') as_dir=./ ;;
+    */) ;;
+    *) as_dir=$as_dir/ ;;
+  esac
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
+    ac_cv_path_MONTAGE="$as_dir$ac_word$ac_exec_ext"
+    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac ;;
+esac
+fi
+MONTAGE=$ac_cv_path_MONTAGE
+if test -n "$MONTAGE"; then
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $MONTAGE" >&5
+printf "%s\n" "$MONTAGE" >&6; }
+else
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+fi
+
+
+  test -n "$MONTAGE" && break
+done
+test -n "$MONTAGE" || MONTAGE="no"
+
+
+   if test "$MONTAGE" = "no" ; then
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: Can not find imagemagick 'montage' executable." >&5
+printf "%s\n" "$as_me: WARNING: Can not find imagemagick 'montage' executable." >&2;}
+   fi
+
+   for ac_prog in xdg-open open
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+printf %s "checking for $ac_word... " >&6; }
+if test ${ac_cv_path_XDG_OPEN+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) case $XDG_OPEN in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_XDG_OPEN="$XDG_OPEN" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  case $as_dir in #(((
+    '') as_dir=./ ;;
+    */) ;;
+    *) as_dir=$as_dir/ ;;
+  esac
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
+    ac_cv_path_XDG_OPEN="$as_dir$ac_word$ac_exec_ext"
+    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac ;;
+esac
+fi
+XDG_OPEN=$ac_cv_path_XDG_OPEN
+if test -n "$XDG_OPEN"; then
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $XDG_OPEN" >&5
+printf "%s\n" "$XDG_OPEN" >&6; }
+else
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+fi
+
+
+  test -n "$XDG_OPEN" && break
+done
+test -n "$XDG_OPEN" || XDG_OPEN="no"
+
+
+   if test "$XDG_OPEN" = "no" ; then
+      as_fn_error $? "Can not find xdg-open." "$LINENO" 5
+      exit 1;
+   fi
+
+   for ac_prog in pkg-config
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+printf %s "checking for $ac_word... " >&6; }
+if test ${ac_cv_path_PKG_CONFIG+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) case $PKG_CONFIG in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  case $as_dir in #(((
+    '') as_dir=./ ;;
+    */) ;;
+    *) as_dir=$as_dir/ ;;
+  esac
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
+    ac_cv_path_PKG_CONFIG="$as_dir$ac_word$ac_exec_ext"
+    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac ;;
+esac
+fi
+PKG_CONFIG=$ac_cv_path_PKG_CONFIG
+if test -n "$PKG_CONFIG"; then
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
+printf "%s\n" "$PKG_CONFIG" >&6; }
+else
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+fi
+
+
+  test -n "$PKG_CONFIG" && break
+done
+test -n "$PKG_CONFIG" || PKG_CONFIG="no"
+
+
+   COMPLETION_DIR=""
+   if test "$PKG_CONFIG" != "no" ; then
+      COMPLETION_DIR=`pkg-config --variable=completionsdir bash-completion`
+
+   fi
+
+   for ac_prog in wish
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+printf %s "checking for $ac_word... " >&6; }
+if test ${ac_cv_path_WISH+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) case $WISH in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_WISH="$WISH" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  case $as_dir in #(((
+    '') as_dir=./ ;;
+    */) ;;
+    *) as_dir=$as_dir/ ;;
+  esac
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir$ac_word$ac_exec_ext"; then
+    ac_cv_path_WISH="$as_dir$ac_word$ac_exec_ext"
+    printf "%s\n" "$as_me:${as_lineno-$LINENO}: found $as_dir$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac ;;
+esac
+fi
+WISH=$ac_cv_path_WISH
+if test -n "$WISH"; then
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $WISH" >&5
+printf "%s\n" "$WISH" >&6; }
+else
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+fi
+
+
+  test -n "$WISH" && break
+done
+test -n "$WISH" || WISH="no"
+
+
+   if test "$WISH" = "no" ; then
+      as_fn_error $? "Can not find TK interpreter executable." "$LINENO" 5
+      exit 1;
+   fi
+
+   for ac_prog in sdl2-config
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.
 set dummy $ac_prog; ac_word=$2
@@ -8243,9 +8246,187 @@ done
 test -n "$SDL2_CONFIG" || SDL2_CONFIG="no"
 
 
-if test "$SDL2_CONFIG" = "no" ; then
-   as_fn_error $? "Can not find libsdl2 development library." "$LINENO" 5
-   exit 1;
+   if test "$SDL2_CONFIG" = "no" ; then
+      as_fn_error $? "Can not find libsdl2 development library." "$LINENO" 5
+      exit 1;
+   fi
+
+   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for tjInitDecompress in -lturbojpeg" >&5
+printf %s "checking for tjInitDecompress in -lturbojpeg... " >&6; }
+if test ${ac_cv_lib_turbojpeg_tjInitDecompress+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) ac_check_lib_save_LIBS=$LIBS
+LIBS="-lturbojpeg  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.
+   The 'extern "C"' is for builds by C++ compilers;
+   although this is not generally supported in C code supporting it here
+   has little cost and some practical benefit (sr 110532).  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char tjInitDecompress (void);
+int
+main (void)
+{
+return tjInitDecompress ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_lib_turbojpeg_tjInitDecompress=yes
+else case e in #(
+  e) ac_cv_lib_turbojpeg_tjInitDecompress=no ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_turbojpeg_tjInitDecompress" >&5
+printf "%s\n" "$ac_cv_lib_turbojpeg_tjInitDecompress" >&6; }
+if test "x$ac_cv_lib_turbojpeg_tjInitDecompress" = xyes
+then :
+  printf "%s\n" "#define HAVE_LIBTURBOJPEG 1" >>confdefs.h
+
+  LIBS="-lturbojpeg $LIBS"
+
+else case e in #(
+  e) as_fn_error $? "Can not find libturbojpeg0." "$LINENO" 5 ;;
+esac
+fi
+
+
+   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for TTF_Init in -lSDL2_ttf" >&5
+printf %s "checking for TTF_Init in -lSDL2_ttf... " >&6; }
+if test ${ac_cv_lib_SDL2_ttf_TTF_Init+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) ac_check_lib_save_LIBS=$LIBS
+LIBS="-lSDL2_ttf  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.
+   The 'extern "C"' is for builds by C++ compilers;
+   although this is not generally supported in C code supporting it here
+   has little cost and some practical benefit (sr 110532).  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char TTF_Init (void);
+int
+main (void)
+{
+return TTF_Init ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_lib_SDL2_ttf_TTF_Init=yes
+else case e in #(
+  e) ac_cv_lib_SDL2_ttf_TTF_Init=no ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_SDL2_ttf_TTF_Init" >&5
+printf "%s\n" "$ac_cv_lib_SDL2_ttf_TTF_Init" >&6; }
+if test "x$ac_cv_lib_SDL2_ttf_TTF_Init" = xyes
+then :
+  printf "%s\n" "#define HAVE_LIBSDL2_TTF 1" >>confdefs.h
+
+  LIBS="-lSDL2_ttf $LIBS"
+
+else case e in #(
+  e) as_fn_error $? "Can not find libsdl ttf." "$LINENO" 5 ;;
+esac
+fi
+
+
+
+    ac_header= ac_cache=
+for ac_item in $ac_header_c_list
+do
+  if test $ac_cache; then
+    ac_fn_c_check_header_compile "$LINENO" $ac_header ac_cv_header_$ac_cache "$ac_includes_default"
+    if eval test \"x\$ac_cv_header_$ac_cache\" = xyes; then
+      printf "%s\n" "#define $ac_item 1" >> confdefs.h
+    fi
+    ac_header= ac_cache=
+  elif test $ac_header; then
+    ac_cache=$ac_item
+  else
+    ac_header=$ac_item
+  fi
+done
+
+
+
+
+
+
+
+
+if test $ac_cv_header_stdlib_h = yes && test $ac_cv_header_string_h = yes
+then :
+
+printf "%s\n" "#define STDC_HEADERS 1" >>confdefs.h
+
+fi
+ac_fn_c_check_header_compile "$LINENO" "turbojpeg.h" "ac_cv_header_turbojpeg_h" "$ac_includes_default"
+if test "x$ac_cv_header_turbojpeg_h" = xyes
+then :
+
+else case e in #(
+  e) as_fn_error $? "Can not find libturbojpeg0 headers file." "$LINENO" 5 ;;
+esac
+fi
+
+
+    CFLAGS=`sdl2-config --cflags`
+
+
+    ac_fn_c_check_header_compile "$LINENO" "SDL.h" "ac_cv_header_SDL_h" "$ac_includes_default"
+if test "x$ac_cv_header_SDL_h" = xyes
+then :
+
+else case e in #(
+  e) as_fn_error $? "Can not find SDL headers file." "$LINENO" 5 ;;
+esac
+fi
+
+
+    ac_fn_c_check_header_compile "$LINENO" "SDL_ttf.h" "ac_cv_header_SDL_ttf_h" "$ac_includes_default"
+if test "x$ac_cv_header_SDL_ttf_h" = xyes
+then :
+
+else case e in #(
+  e) as_fn_error $? "Can not find sdl ttf header file." "$LINENO" 5 ;;
+esac
+fi
+
+
+else
+   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: GUI has been disabled  " >&5
+printf "%s\n" "$as_me: GUI has been disabled  " >&6;}
 fi
 
  if test "$COMPLETION_DIR" != ""; then
@@ -8425,178 +8606,6 @@ esac
 fi
 
 
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for tjInitDecompress in -lturbojpeg" >&5
-printf %s "checking for tjInitDecompress in -lturbojpeg... " >&6; }
-if test ${ac_cv_lib_turbojpeg_tjInitDecompress+y}
-then :
-  printf %s "(cached) " >&6
-else case e in #(
-  e) ac_check_lib_save_LIBS=$LIBS
-LIBS="-lturbojpeg  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.
-   The 'extern "C"' is for builds by C++ compilers;
-   although this is not generally supported in C code supporting it here
-   has little cost and some practical benefit (sr 110532).  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char tjInitDecompress (void);
-int
-main (void)
-{
-return tjInitDecompress ();
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"
-then :
-  ac_cv_lib_turbojpeg_tjInitDecompress=yes
-else case e in #(
-  e) ac_cv_lib_turbojpeg_tjInitDecompress=no ;;
-esac
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS ;;
-esac
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_turbojpeg_tjInitDecompress" >&5
-printf "%s\n" "$ac_cv_lib_turbojpeg_tjInitDecompress" >&6; }
-if test "x$ac_cv_lib_turbojpeg_tjInitDecompress" = xyes
-then :
-  printf "%s\n" "#define HAVE_LIBTURBOJPEG 1" >>confdefs.h
-
-  LIBS="-lturbojpeg $LIBS"
-
-else case e in #(
-  e) as_fn_error $? "Can not find libturbojpeg0." "$LINENO" 5 ;;
-esac
-fi
-
-
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for TTF_Init in -lSDL2_ttf" >&5
-printf %s "checking for TTF_Init in -lSDL2_ttf... " >&6; }
-if test ${ac_cv_lib_SDL2_ttf_TTF_Init+y}
-then :
-  printf %s "(cached) " >&6
-else case e in #(
-  e) ac_check_lib_save_LIBS=$LIBS
-LIBS="-lSDL2_ttf  $LIBS"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.
-   The 'extern "C"' is for builds by C++ compilers;
-   although this is not generally supported in C code supporting it here
-   has little cost and some practical benefit (sr 110532).  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char TTF_Init (void);
-int
-main (void)
-{
-return TTF_Init ();
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"
-then :
-  ac_cv_lib_SDL2_ttf_TTF_Init=yes
-else case e in #(
-  e) ac_cv_lib_SDL2_ttf_TTF_Init=no ;;
-esac
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS ;;
-esac
-fi
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_SDL2_ttf_TTF_Init" >&5
-printf "%s\n" "$ac_cv_lib_SDL2_ttf_TTF_Init" >&6; }
-if test "x$ac_cv_lib_SDL2_ttf_TTF_Init" = xyes
-then :
-  printf "%s\n" "#define HAVE_LIBSDL2_TTF 1" >>confdefs.h
-
-  LIBS="-lSDL2_ttf $LIBS"
-
-else case e in #(
-  e) as_fn_error $? "Can not find libsdl ttf." "$LINENO" 5 ;;
-esac
-fi
-
-
-
-ac_header= ac_cache=
-for ac_item in $ac_header_c_list
-do
-  if test $ac_cache; then
-    ac_fn_c_check_header_compile "$LINENO" $ac_header ac_cv_header_$ac_cache "$ac_includes_default"
-    if eval test \"x\$ac_cv_header_$ac_cache\" = xyes; then
-      printf "%s\n" "#define $ac_item 1" >> confdefs.h
-    fi
-    ac_header= ac_cache=
-  elif test $ac_header; then
-    ac_cache=$ac_item
-  else
-    ac_header=$ac_item
-  fi
-done
-
-
-
-
-
-
-
-
-if test $ac_cv_header_stdlib_h = yes && test $ac_cv_header_string_h = yes
-then :
-
-printf "%s\n" "#define STDC_HEADERS 1" >>confdefs.h
-
-fi
-ac_fn_c_check_header_compile "$LINENO" "turbojpeg.h" "ac_cv_header_turbojpeg_h" "$ac_includes_default"
-if test "x$ac_cv_header_turbojpeg_h" = xyes
-then :
-
-else case e in #(
-  e) as_fn_error $? "Can not find libturbojpeg0 headers file." "$LINENO" 5 ;;
-esac
-fi
-
-
-CFLAGS=`sdl2-config --cflags`
-
-
-ac_fn_c_check_header_compile "$LINENO" "SDL.h" "ac_cv_header_SDL_h" "$ac_includes_default"
-if test "x$ac_cv_header_SDL_h" = xyes
-then :
-
-else case e in #(
-  e) as_fn_error $? "Can not find SDL headers file." "$LINENO" 5 ;;
-esac
-fi
-
-
-ac_fn_c_check_header_compile "$LINENO" "SDL_ttf.h" "ac_cv_header_SDL_ttf_h" "$ac_includes_default"
-if test "x$ac_cv_header_SDL_ttf_h" = xyes
-then :
-
-else case e in #(
-  e) as_fn_error $? "Can not find sdl ttf header file." "$LINENO" 5 ;;
-esac
-fi
-
 
 ac_config_files="$ac_config_files Makefile quick_quicklisp.sh po/Makefile.in src/config.lisp.in"
 
diff --git a/configure.ac b/configure.ac
index 3494f0a..e9dc7c6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -60,7 +60,7 @@ AC_ARG_WITH([dynamic-memory-size], [AS_HELP_STRING([--with-dynamic-memory-size=s
 
 AC_SUBST(DYNAMIC_MEMORY_SIZE,[$DYNAMIC_MEMORY_SIZE])
 
-AC_ARG_ENABLE([gui], [AS_HELP_STRING([--enable-gui], [enable GUI default: 'enabled'])], [GUI=yes], [GUI=no])
+AC_ARG_ENABLE([gui], [AS_HELP_STRING([--disable-gui], [disable GUI default: 'enabled'])], [GUI=$enableval], [GUI=yes])
 
 AC_SUBST(GUI,[$GUI])
 
@@ -104,13 +104,6 @@ if test -z "${AWK}"; then
    exit 1
 fi
 
-AC_PATH_PROGS([XDG_OPEN],[xdg-open open],[no])
-
-if test "$XDG_OPEN" = "no" ; then
-   AC_MSG_ERROR([Can not find xdg-open.])
-   exit 1;
-fi
-
 AC_PATH_PROGS([OPENSSL],[openssl],[no])
 
 if test "$OPENSSL" = "no" ; then
@@ -139,12 +132,6 @@ if test "$DIRNAME" = "no" ; then
    exit 1;
 fi
 
-AC_PATH_PROGS([MONTAGE],[montage montage-im6.q16 montage-im6],[no])
-
-if test "$MONTAGE" = "no" ; then
-   AC_MSG_WARN([Can not find imagemagick 'montage' executable.])
-fi
-
 AC_PATH_PROGS([FILE],[file],[no])
 
 if test "$FILE" = "no" ; then
@@ -152,21 +139,6 @@ if test "$FILE" = "no" ; then
    exit 1;
 fi
 
-AC_PATH_PROGS([PKG_CONFIG],[pkg-config],[no])
-
-COMPLETION_DIR=""
-if test "$PKG_CONFIG" != "no" ; then
-   COMPLETION_DIR=`pkg-config --variable=completionsdir bash-completion`
-   AC_SUBST([COMPLETION_DIR])
-fi
-
-AC_PATH_PROGS([WISH],[wish],[no])
-
-if test "$WISH" = "no" ; then
-   AC_MSG_ERROR([Can not find TK interpreter executable.])
-   exit 1;
-fi
-
 AC_PATH_PROGS([WHICH],[which],[no])
 
 if test "$WHICH" = "no" ; then
@@ -174,11 +146,61 @@ if test "$WHICH" = "no" ; then
    exit 1;
 fi
 
-AC_PATH_PROGS([SDL2_CONFIG],[sdl2-config],[no])
+dnl the following tests can be skipped if GUI has not been enabled
 
-if test "$SDL2_CONFIG" = "no" ; then
-   AC_MSG_ERROR([Can not find libsdl2 development library.])
-   exit 1;
+if test "$GUI" = "yes" ; then
+
+   AC_PATH_PROGS([MONTAGE],[montage montage-im6.q16 montage-im6],[no])
+
+   if test "$MONTAGE" = "no" ; then
+      AC_MSG_WARN([Can not find imagemagick 'montage' executable.])
+   fi
+
+   AC_PATH_PROGS([XDG_OPEN],[xdg-open open],[no])
+
+   if test "$XDG_OPEN" = "no" ; then
+      AC_MSG_ERROR([Can not find xdg-open.])
+      exit 1;
+   fi
+
+   AC_PATH_PROGS([PKG_CONFIG],[pkg-config],[no])
+
+   COMPLETION_DIR=""
+   if test "$PKG_CONFIG" != "no" ; then
+      COMPLETION_DIR=`pkg-config --variable=completionsdir bash-completion`
+      AC_SUBST([COMPLETION_DIR])
+   fi
+
+   AC_PATH_PROGS([WISH],[wish],[no])
+
+   if test "$WISH" = "no" ; then
+      AC_MSG_ERROR([Can not find TK interpreter executable.])
+      exit 1;
+   fi
+
+   AC_PATH_PROGS([SDL2_CONFIG],[sdl2-config],[no])
+
+   if test "$SDL2_CONFIG" = "no" ; then
+      AC_MSG_ERROR([Can not find libsdl2 development library.])
+      exit 1;
+   fi
+
+   AC_CHECK_LIB([turbojpeg], [tjInitDecompress], [], AC_MSG_ERROR([Can not find libturbojpeg0.]))
+
+   AC_CHECK_LIB([SDL2_ttf], [TTF_Init], [], AC_MSG_ERROR([Can not find libsdl ttf.]))
+
+dnl check headers
+
+    AC_CHECK_HEADER([turbojpeg.h], [], AC_MSG_ERROR([Can not find libturbojpeg0 headers file.]), [])
+
+    AC_SUBST([CFLAGS], [`sdl2-config --cflags`])
+
+    AC_CHECK_HEADER([SDL.h], [], AC_MSG_ERROR([Can not find SDL headers file.]), [])
+
+    AC_CHECK_HEADER([SDL_ttf.h], [], AC_MSG_ERROR([Can not find sdl ttf header file.]), [])
+
+else
+   AC_MSG_NOTICE(GUI has been disabled  )
 fi
 
 AM_CONDITIONAL([ENABLE_COMPLETION],[test "$COMPLETION_DIR" != ""])
@@ -193,19 +215,6 @@ AC_CHECK_LIB([ncurses], [initscr], [], AC_MSG_ERROR([Can not find ncurses.]))
 
 AC_CHECK_LIB([sqlite3], [sqlite3_libversion], [], AC_MSG_ERROR([Can not find libsqlite3.]))
 
-AC_CHECK_LIB([turbojpeg], [tjInitDecompress], [], AC_MSG_ERROR([Can not find libturbojpeg0.]))
-
-AC_CHECK_LIB([SDL2_ttf], [TTF_Init], [], AC_MSG_ERROR([Can not find libsdl ttf.]))
-
-dnl check headers
-
-AC_CHECK_HEADER([turbojpeg.h], [], AC_MSG_ERROR([Can not find libturbojpeg0 headers file.]), [])
-
-AC_SUBST([CFLAGS], [`sdl2-config --cflags`])
-
-AC_CHECK_HEADER([SDL.h], [], AC_MSG_ERROR([Can not find SDL headers file.]), [])
-
-AC_CHECK_HEADER([SDL_ttf.h], [], AC_MSG_ERROR([Can not find sdl ttf header file.]), [])
 
 AC_CONFIG_FILES([Makefile quick_quicklisp.sh po/Makefile.in src/config.lisp.in])