Simplified the control nesting model by removing Control.unparent() and requiring all Windows to have a Control at construct time; implemented such on Windows.

redo/containers_windows.go

@@ -20,7 +20,6 @@ TODO
 type tab struct {
 	*widgetbase
 	tabs			[]Control
-	curparent		*window
 }
 
 func newTab() Tab {
@@ -35,28 +34,17 @@ func newTab() Tab {
 	return t
 }
 
-func (t *tab) unparent() {
-	t.widgetbase.unparent()
+func (t *tab) setParent(win C.HWND) {
+	t.widgetbase.setParent(win)
 	for _, c := range t.tabs {
-		c.unparent()
+		c.setParent(win)
 	}
-	t.curparent = nil
-}
-
-func (t *tab) parent(win *window) {
-	t.widgetbase.parent(win)
-	for _, c := range t.tabs {
-		c.parent(win)
-	}
-	t.curparent = win
 }
 
 func (t *tab) Append(name string, control Control) {
 	t.tabs = append(t.tabs, control)
-	if t.curparent == nil {
-		control.unparent()
-	} else {
-		control.parent(t.curparent)
+	if t.parent != nil {
+		control.setParent(t.parent)
 	}
 	C.tabAppend(t.hwnd, toUTF16(name))
 }

redo/controls.go

@@ -5,8 +5,7 @@ package ui
 // Control represents a control.
 // All Controls have event handlers that take a single argument (the Doer active during the event) and return nothing.
 type Control interface {
-	unparent()
-	parent(*window)
+	controlParent			// platform-specific
 	// TODO enable/disable (public)
 	// TODO show/hide (public)
 	containerShow()		// for Windows, where all controls need ot belong to an overlapped window, not to a container control; these respect programmer settings

redo/controls_windows.go

@@ -11,6 +11,7 @@ import "C"
 
 type widgetbase struct {
 	hwnd	C.HWND
+	parent	C.HWND
 }
 
 func newWidget(class C.LPCWSTR, style C.DWORD, extstyle C.DWORD) *widgetbase {
@@ -21,13 +22,9 @@ func newWidget(class C.LPCWSTR, style C.DWORD, extstyle C.DWORD) *widgetbase {
 
 // these few methods are embedded by all the various Controls since they all will do the same thing
 
-func (w *widgetbase) unparent() {
-	C.controlSetParent(w.hwnd, C.msgwin)
-}
-
-func (w *widgetbase) parent(win *window) {
-	C.controlSetParent(w.hwnd, win.hwnd)
-	// TODO new control does not show up until window is resized
+func (w *widgetbase) setParent(win C.HWND) {
+	C.controlSetParent(w.hwnd, win)
+	w.parent = win
 }
 
 func (w *widgetbase) containerShow() {

redo/window.go

@@ -6,9 +6,6 @@ package ui
 // Windows in package ui can only contain one control; the Stack and Grid layout Controls allow you to pack multiple Controls in a Window.
 // Note that a Window is not itself a Control.
 type Window interface {
-	// SetControl sets the Window's child Control.
-	SetControl(c Control)
-
 	// Title and SetTitle get and set the Window's title, respectively.
 	Title() string
 	SetTitle(title string)
@@ -30,20 +27,7 @@ type Window interface {
 	OnClosing(func() bool)
 }
 
-// NewWindow creates a new Window with the given title text and size.
-func NewWindow(title string, width int, height int) Window {
-	return newWindow(title, width, height)
-}
-
-// everything below is kept here because they're the same on all platforms
-// TODO move event stuff here and make windowbase
-
-func (w *window) SetControl(control Control) {
-	if w.child != nil {		// unparent existing control
-		w.child.unparent()
-	}
-	control.unparent()
-	control.parent(w)
-	w.child = control
-	// each call to unparent() and parent() will cause the old/new parents to be redrawn; we don't have to worry about that here
+// NewWindow creates a new Window with the given title text, size, and control.
+func NewWindow(title string, width int, height int, control Control) Window {
+	return newWindow(title, width, height, control)
 }

redo/window_windows.go

@@ -35,7 +35,11 @@ func makeWindowWindowClass() error {
 	return nil
 }
 
-func newWindow(title string, width int, height int) *window {
+type controlParent interface {
+	setParent(C.HWND)
+}
+
+func newWindow(title string, width int, height int, control Control) *window {
 	w := &window{
 		// hwnd set in WM_CREATE handler
 		closing:	newEvent(),
@@ -49,6 +53,8 @@ func newWindow(title string, width int, height int) *window {
 	if hresult != C.S_OK {
 		panic(fmt.Errorf("error setting tab background texture on Window; HRESULT: 0x%X", hresult))
 	}
+	w.child = control
+	w.child.setParent(w.hwnd)
 	return w
 }
 

redo/zz_test.go

@@ -18,13 +18,8 @@ func init() {
 	go func() {
 		done := make(chan struct{})
 		Do(func() {
-			w := NewWindow("Hello", 320, 240)
-			b := NewButton("There")
 			t := NewTab()
-			w.SetControl(t)
-			if *closeOnClick {
-				b.SetText("Click to Close")
-			}
+			w := NewWindow("Hello", 320, 240, t)
 			w.OnClosing(func() bool {
 				if *closeOnClick {
 					panic("window closed normally in close on click mode (should not happen)")
@@ -34,6 +29,10 @@ func init() {
 				done <- struct{}{}
 				return true
 			})
+			b := NewButton("There")
+			if *closeOnClick {
+				b.SetText("Click to Close")
+			}
 			// GTK+ TODO: this is causing a resize event to happen afterward?!
 			b.OnClicked(func() {
 				println("in OnClicked()")
@@ -45,10 +44,10 @@ func init() {
 			})
 			t.Append("Button", b)
 			c := NewCheckbox("You Should Now See Me Instead")
-			t.Append("Checkbox", c)
 			c.OnClicked(func() {
 				w.SetTitle(fmt.Sprint(c.Checked()))
 			})
+			t.Append("Checkbox", c)
 			w.Show()
 		})
 		<-done