diff --git a/redo/common_unix.go b/redo/common_unix.go
index e495063..e2d9261 100644
--- a/redo/common_unix.go
+++ b/redo/common_unix.go
@@ -7,6 +7,11 @@ import (
 )
 
 // #include "gtk_unix.h"
+// /* because cgo doesn't like g_signal_connect() */
+// void gSignalConnect(gpointer obj, gchar *sig, GCallback callback, gpointer data)
+// {
+// 	g_signal_connect(obj, sig, callback, data);
+// }
 import "C"
 
 func fromgstr(s *C.gchar) string {
@@ -20,3 +25,9 @@ func togstr(s string) *C.gchar {
 func freegstr(s *C.gchar) {
 	C.free(unsafe.Pointer(s))
 }
+
+func g_signal_connect(object C.gpointer, name string, to C.GCallback, data C.gpointer) {
+	cname := togstr(name)
+	defer freegstr(cname)
+	C.gSignalConnect(object, cname, to, data)
+}
diff --git a/redo/uitask.go b/redo/uitask.go
index 76908fb..462a24b 100644
--- a/redo/uitask.go
+++ b/redo/uitask.go
@@ -45,10 +45,23 @@ type event struct {
 	lock		sync.Mutex
 }
 
+// do should never be nil; TODO should we make setters panic instead?
+
+func newEvent() *event {
+	return &event{
+		do:	func(c Doer) bool {
+			return false
+		},
+	}
+}
+
 func (e *event) set(f func(Doer)) {
 	e.lock.Lock()
 	defer e.lock.Unlock()
 
+	if f == nil {
+		f = func(c Doer) {}
+	}
 	e.do = func(c Doer) bool {
 		f(c)
 		return false
@@ -59,6 +72,11 @@ func (e *event) setbool(f func(Doer) bool) {
 	e.lock.Lock()
 	defer e.lock.Unlock()
 
+	if f == nil {
+		f = func(c Doer) bool {
+			return false
+		}
+	}
 	e.do = f
 }
 
diff --git a/redo/window_unix.go b/redo/window_unix.go
index 6e93fa7..c92fba6 100644
--- a/redo/window_unix.go
+++ b/redo/window_unix.go
@@ -7,6 +7,7 @@ import (
 )
 
 // #include "gtk_unix.h"
+// extern gboolean windowClosing(GtkWidget *, GdkEvent *, gpointer);
 import "C"
 
 type window struct {
@@ -14,6 +15,8 @@ type window struct {
 	container	*C.GtkContainer
 	bin		*C.GtkBin
 	window	*C.GtkWindow
+
+	closing	*event
 }
 
 func newWindow(title string, width int, height int) *Request {
@@ -28,8 +31,14 @@ func newWindow(title string, width int, height int) *Request {
 				container:		(*C.GtkContainer)(unsafe.Pointer(widget)),
 				bin:			(*C.GtkBin)(unsafe.Pointer(widget)),
 				window:		(*C.GtkWindow)(unsafe.Pointer(widget)),
+				closing:		newEvent(),
 			}
 			C.gtk_window_set_title(w.window, ctitle)
+			g_signal_connect(
+				C.gpointer(unsafe.Pointer(w.window)),
+				"delete-event",
+				C.GCallback(C.windowClosing),
+				C.gpointer(unsafe.Pointer(w)))
 			// TODO size
 			// TODO content
 			c <- w
@@ -108,6 +117,22 @@ func (w *window) Close() *Request {
 }
 
 func (w *window) OnClosing(e func(c Doer) bool) *Request {
-	// TODO
-	return nil
+	c := make(chan interface{})
+	return &Request{
+		op:		func() {
+			w.closing.setbool(e)
+			c <- struct{}{}
+		},
+		resp:		c,
+	}
+}
+
+//export windowClosing
+func windowClosing(wid *C.GtkWidget, e *C.GdkEvent, data C.gpointer) C.gboolean {
+	w := (*window)(unsafe.Pointer(data))
+	close := w.closing.fire()
+	if close {
+		return C.GDK_EVENT_PROPAGATE		// will do gtk_widget_destroy(), which is what we want (thanks ebassi in irc.gimp.net/#gtk+)
+	}
+	return C.GDK_EVENT_STOP				// keeps window alive
 }
diff --git a/redo/zz_test.go b/redo/zz_test.go
index a4ff669..122005b 100644
--- a/redo/zz_test.go
+++ b/redo/zz_test.go
@@ -12,10 +12,10 @@ func TestPackage(t *testing.T) {
 	go func() {
 		w := GetNewWindow(Do, "Hello", 320, 240)
 		done := make(chan struct{})
-//		Wait(Do, w.OnClosing(func(Doer) bool {
-//			done <- struct{}{}
-//			return true
-//		}))
+		Wait(Do, w.OnClosing(func(Doer) bool {
+			done <- struct{}{}
+			return true
+		}))
 		Wait(Do, w.Show())
 		<-done
 	}()