Added Stop() and implemented it on Windows.

redo/funcnames_windows.go

@@ -26,3 +26,4 @@ package ui
 // wfunc user32 SendMessageW uintptr t_UINT t_WPARAM t_LPARAM t_LRESULT,noerr
 // wfunc user32 UpdateWindow uintptr uintptr
 // wfunc user32 DestroyWindow uintptr uintptr
+// wfunc user32 PostQuitMessage uintptr void

redo/uitask.go

@@ -19,7 +19,19 @@ func Go() error {
 	return nil
 }
 
-// TODO Stop
+// Stop returns a Request for package ui to stop.
+// Some time after this request is received, Go() will return without performing any final cleanup.
+// If Stop is issued during an event handler, it will be registered when the event handler returns.
+func Stop() *Request {
+	c := make(chan interface{})
+	return &Request{
+		op:		func() {
+			uistop()
+			c <- struct{}{}
+		},
+		resp:		c,
+	}
+}
 
 // This is the ui main loop.
 // It is spawned by Go as a goroutine.

redo/uitask_windows.go

@@ -45,6 +45,11 @@ func uimsgloop() {
 	}
 }
 
+func uistop() {
+	// this works fine as documented in modal loops, as modal loops are supposed to repost quit messages (http://blogs.msdn.com/b/oldnewthing/archive/2005/02/22/378018.aspx), and all the Windows internal ones do
+	f_PostQuitMessage(0)
+}
+
 func issue(req *Request) {
 	res, err := f_PostMessageW(
 		msgwin,

redo/zz_test.go

@@ -13,7 +13,8 @@ func init() {
 	go func() {
 		w := GetNewWindow(Do, "Hello", 320, 240)
 		done := make(chan struct{})
-		Wait(Do, w.OnClosing(func(Doer) bool {
+		Wait(Do, w.OnClosing(func(c Doer) bool {
+			Wait(c, Stop())
 			done <- struct{}{}
 			return true
 		}))