gnu: Add xfwm4.

* gnu/packages/xfce.scm (xfwm4): New variable.

gnu/packages/xfce.scm

@@ -416,3 +416,31 @@ (define-public thunar-volman
 digitcal camera, it will automatically spawn your preferred photo application
 and import the new pictures from your camera.")
     (license gpl2+)))
+
+(define-public xfwm4
+  (package
+    (name "xfwm4")
+    (version "4.10.0")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "http://archive.xfce.org/xfce/"
+                                  (version-major+minor version)
+                                  "/src/" name "-" version ".tar.bz2"))
+              (sha256
+               (base32
+                "170zzs7adj47srsi2cl723w9pl8k8awd7w1bpzxby7hj92zmf8s9"))))
+    (build-system gnu-build-system)
+    (native-inputs
+     `(("pkg-config" ,pkg-config)
+       ("intltool" ,intltool)))
+    (inputs
+     `(("libwnck", libwnck-1)
+       ("libxfce4ui" ,libxfce4ui)
+       ("libxrandr" ,libxrandr)
+       ("libxcomposite" ,libxcomposite)))
+    (home-page "http://www.xfce.org/")
+    (synopsis "Xfce window manager")
+    (description
+     "Window manager for Xfce, it handles the placement of windows
+on the screen.")
+    (license gpl2+)))