x11.xinput2: xi2-available?

basis/x11/xinput2/xinput2.factor

@@ -1,4 +1,17 @@
 ! Copyright (C) 2010 Niklas Waern.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: ;
+USING: alien.c-types combinators kernel namespaces x11
+x11.constants x11.xinput2.ffi ;
 IN: x11.xinput2
+
+: (xi2-available?) ( display -- ? )
+    2 0 [ <int> ] bi@
+    XIQueryVersion
+    {
+        { BadRequest [ f ] }
+        { Success    [ t ] }
+        [ "Internal Xlib error." throw ]
+    } case ;
+
+: xi2-available? ( -- ? ) dpy get (xi2-available?) ; inline
+