Made event handler setters return a Request, implemented stubs on GTK+ so I can build a test, and made documentation consistent.

redo/controls.go

@@ -15,15 +15,15 @@ type Control interface {
 type Button interface {
 	Control
 
-	// OnClicked sets the event handler for when the Button is clicked.
-	OnClicked(func(d Doer))
+	// OnClicked creates a Request to set the event handler for when the Button is clicked.
+	OnClicked(func(d Doer)) *Request
 
-	// Text and SetText are Requests that get and set the Button's label text.
+	// Text and SetText creates a Request that get and set the Button's label text.
 	Text() *Request
 	SetText(text string) *Request
 }
 
-// NewButton returns a Request to create a new Button with the given label text.
+// NewButton creates a Request to create a new Button with the given label text.
 func NewButton(text string) *Request {
 	return newButton(text)
 }

redo/controls_unix.go

@@ -40,7 +40,10 @@ func newButton(text string) *Request {
 	}
 }
 
-// TODO OnClicked
+func (b *Button) OnClicked(func e(c Doer)) *Request {
+	// TODO
+	return nil
+}
 
 func (b *button) Text() *Request {
 	c := make(chan interface{})

redo/window.go

@@ -22,11 +22,11 @@ type Window interface {
 	// Attempting to use a Window after it has been closed results in undefined behavior.
 	Close() *Request
 
-	// OnClosing registers an event handler that is triggered when the user clicks the Window's close button.
+	// OnClosing creates a Request to register an event handler that is triggered when the user clicks the Window's close button.
 	// On systems where whole applications own windows, OnClosing is also triggered when the user asks to close the application.
 	// If this handler returns true, the Window is closed as defined by Close above.
 	// If this handler returns false, the Window is not closed.
-	OnClosing(func(c Doer) bool)
+	OnClosing(func(c Doer) bool) *Request
 
 	// TODO SetSize (TODO remove?)
 	// TODO Center

redo/window_unix.go

@@ -107,4 +107,7 @@ func (w *window) Close() *Request {
 	}
 }
 
-// TODO OnClosing
+func (w *window) OnClosing(func e(c Doer) bool) *Request {
+	// TODO
+	return nil
+}