Changed GTK+ configure option.

configure.ac

@@ -79,28 +79,35 @@ PKG_CHECK_MODULES(GLIB2, [
 ])
 
 dnl - check gtk
-AC_ARG_WITH(gtk-version,
-    AS_HELP_STRING([--with-gtk-version[=VERSION]],
-                   [Select GTK+ version. The default is 2]),,
-    with_gtk_version=2
+AC_ARG_WITH([gtk],
+    [AS_HELP_STRING([--with-gtk=2.0|3.0],
+                    [Select GTK+ version. The default is 2.0])],
+    [case "$with_gtk" in
+        2.0|3.0) ;;
+        *) AC_MSG_ERROR([invalid gtk version specified]) ;;
+     esac],
+    [with_gtk=2.0]
 )
 
-if test "x$with_gtk_version" = x3 ; then
-    PKG_CHECK_MODULES(GTK3, [
-        gtk+-3.0
-    ])
-    AM_CONDITIONAL(HAVE_GTK3, true)
-    AM_CONDITIONAL(HAVE_GTK2, false)
-    WITH_GTK_VERSION=3.0
-else
-    PKG_CHECK_MODULES(GTK2, [
-        gtk+-2.0
-    ])
-    AM_CONDITIONAL(HAVE_GTK3, false)
-    AM_CONDITIONAL(HAVE_GTK2, true)
-    WITH_GTK_VERSION=2.0
-fi
-AC_SUBST(WITH_GTK_VERSION)
+case "$with_gtk" in
+    2.0)
+        PKG_CHECK_MODULES(GTK2, [
+            gtk+-2.0
+        ])
+        AM_CONDITIONAL(HAVE_GTK3, false)
+        AM_CONDITIONAL(HAVE_GTK2, true)
+        GTK_API_VERSION=2.0
+        ;;
+    3.0)
+        PKG_CHECK_MODULES(GTK3, [
+            gtk+-3.0
+        ])
+        AM_CONDITIONAL(HAVE_GTK3, true)
+        AM_CONDITIONAL(HAVE_GTK2, false)
+        GTK_API_VERSION=3.0
+    ;;
+esac
+AC_SUBST(GTK_API_VERSION)
 
 PKG_CHECK_MODULES(LIBXML2, [
     libxml-2.0 >= 2.0
@@ -228,7 +235,7 @@ echo "
 
 
 libinput_pad version:    $libinput_pad_VERSION
-GTK+ version:            $WITH_GTK_VERSION
+GTK+ version:            $GTK_API_VERSION
 Have libxklavier:        $have_libxklavier
 Enable EEK               $enable_eek
 Enable Python            $enable_python

input-pad.pc.in

@@ -8,6 +8,6 @@ xkeysenddir=@libdir@/input-pad-@libinput_pad_VERSION@/modules/xkeysend
 Name: input-pad
 Description: Input Pad
 Version: @VERSION@
-Requires: glib-2.0 gtk+-@WITH_GTK_VERSION@
+Requires: glib-2.0 gtk+-@GTK_API_VERSION@
 Cflags: -I${includedir}
 Libs: -L${libdir} -linput-pad