Began final simplification of size code. spaced is now a global variable; either all controls are given spacing now, or none will. beginResize() is a method on container again. Done on GTK+ and Mac OS X for now. I'm going to go ahead and implement this on Windows in a bit, regardless of whether that Stack Overflow question get answered or not, because ugggggggggh I just want to continue working on this project for fuck's sake!

redo/containers_darwin.go

@@ -25,7 +25,6 @@ func newTab() Tab {
 func (t *tab) Append(name string, control Control) {
 	// TODO isolate and standardize
 	c := new(container)
-	// don't set beginResize; this container's resize() will be a recursive call
 	t.containers = append(t.containers, c)
 	cname := C.CString(name)
 	defer C.free(unsafe.Pointer(cname))
@@ -35,11 +34,7 @@ func (t *tab) Append(name string, control Control) {
 }
 
 func (t *tab) allocate(x int, y int, width int, height int, d *sizing) []*allocation {
-	// set up the recursive calls
-	for _, c := range t.containers {
-		c.d = d
-	}
-	// and prepare the tabbed control itself
+	// only prepared the tabbed control; its children will be reallocated when that one is resized
 	return t.widgetbase.allocate(x, y, width, height, d)
 }
 

redo/containers_unix.go

@@ -40,7 +40,6 @@ func (t *tab) Append(name string, control Control) {
 	t.layoutcs = append(t.layoutcs, (*C.GtkContainer)(unsafe.Pointer(layout)))
 	t.layouts = append(t.layouts, (*C.GtkLayout)(unsafe.Pointer(layout)))
 	c := new(container)
-	// don't set beginResize; this container's resize() will be a recursive call
 	t.containers = append(t.containers, c)
 	c.child = control
 	c.child.setParent((*C.GtkContainer)(unsafe.Pointer(layout)))
@@ -60,11 +59,7 @@ func (t *tab) Append(name string, control Control) {
 }
 
 func (t *tab) allocate(x int, y int, width int, height int, d *sizing) []*allocation {
-	// set up the recursive calls
-	for _, c := range t.containers {
-		c.d = d
-	}
-	// and prepare the tabbed control itself
+	// only prepared the tabbed control; its children will be reallocated when that one is resized
 	return t.widgetbase.allocate(x, y, width, height, d)
 }
 

redo/sizing.go

@@ -29,24 +29,20 @@ type controlSizing interface {
 // on GTK+ and Mac OS X, one is embedded by window and all containers; beginResize() points to a global function (TODO NOT GOOD; ideally the sizing data should be passed across size-allocate requests)
 type container struct {
 	child		Control
-	spaced	bool
-	d		*sizing
 }
 
+// set to true to apply spacing to all windows
+var spaced bool = false
+
 func (c *container) resize(width, height int) {
 	if c.child == nil {		// no children; nothing to do
 		return
 	}
-	if c.d == nil {			// not ready (called early or out of the proper recursive call chain (such as by the underlying system when marking an unparented Tab as shown))
-		return
-	}
-	d := c.d
+	d := c.beginResize()
 	allocations := c.child.allocate(0 + d.xmargin, 0 + d.ymargin, width - (2 * d.xmargin), height - (2 * d.ymargin), d)
 	c.translateAllocationCoords(allocations, width, height)
 	// move in reverse so as to approximate right->left order so neighbors make sense
 	for i := len(allocations) - 1; i >= 0; i-- {
 		allocations[i].this.commitResize(allocations[i], d)
 	}
-	// always set c.d to nil so it can be garbage-collected
-	c.d = nil
 }

redo/sizing_darwin.go

@@ -24,9 +24,9 @@ const (
 	macYPadding = 12
 )
 
-func (w *window) beginResize() (d *sizing) {
+func (c *container) beginResize() (d *sizing) {
 	d = new(sizing)
-	if w.spaced {
+	if spaced {
 		d.xmargin = macXMargin
 		d.ymargin = macYMargin
 		d.xpadding = macXPadding

redo/sizing_unix.go

@@ -24,9 +24,9 @@ const (
 	gtkYPadding = 6
 )
 
-func (w *window) beginResize() (d *sizing) {
+func (c *container) beginResize() (d *sizing) {
 	d = new(sizing)
-	if w.spaced {
+	if spaced {
 		d.xmargin = gtkXMargin
 		d.ymargin = gtkYMargin
 		d.xpadding = gtkXPadding

redo/window_darwin.go

@@ -77,7 +77,6 @@ func windowClosing(xw unsafe.Pointer) C.BOOL {
 //export windowResized
 func windowResized(xw unsafe.Pointer, width C.uintptr_t, height C.uintptr_t) {
 	w := (*window)(unsafe.Pointer(xw))
-	w.container.d = w.beginResize()
 	w.resize(int(width), int(height))
 	fmt.Printf("new size %d x %d\n", width, height)
 }

redo/window_unix.go

@@ -110,7 +110,6 @@ func windowClosing(wid *C.GtkWidget, e *C.GdkEvent, data C.gpointer) C.gboolean
 //export windowResizing
 func windowResizing(wid *C.GtkWidget, r *C.GdkRectangle, data C.gpointer) {
 	w := (*window)(unsafe.Pointer(data))
-	w.container.d = w.beginResize()
 	w.resize(int(r.width), int(r.height))
 	fmt.Printf("new size %d x %d\n", r.width, r.height)
 }

redo/zz_test.go

@@ -11,18 +11,16 @@ import (
 )
 
 var closeOnClick = flag.Bool("close", false, "close on click")
-var spaced = flag.Bool("spaced", false, "enable spacing")
 
 // because Cocoa hates being run off the main thread, even if it's run exclusively off the main thread
 func init() {
+	flag.BoolVar(&spaced, "spaced", false, "enable spacing")
 	flag.Parse()
 	go func() {
 		done := make(chan struct{})
 		Do(func() {
 			t := NewTab()
 			w := NewWindow("Hello", 320, 240, t)
-			// TODO use a method here
-			w.(*window).spaced = *spaced
 			w.OnClosing(func() bool {
 				if *closeOnClick {
 					panic("window closed normally in close on click mode (should not happen)")