Changed window resizes so that the actual Control.setRect() functions appended to an array of requests that the resize() function set all at once instead of having each done individually. This will be necessary for what I think will be a solution to the deadlocks. It doesn't work right now; I'm assuming it's allocating too much memory. I know how to fix this, but I'm committing what I have so far to be safe.

area.go

@@ -121,8 +121,14 @@ func (a *Area) make(window *sysData) error {
 	return nil
 }
 
-func (a *Area) setRect(x int, y int, width int, height int, winheight int) error {
-	return a.sysData.setRect(x, y, width, height, winheight)
+func (a *Area) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	a.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (a *Area) preferredSize() (width int, height int) {

button.go

@@ -61,8 +61,14 @@ func (b *Button) make(window *sysData) error {
 	return nil
 }
 
-func (b *Button) setRect(x int, y int, width int, height int, winheight int) error {
-	return b.sysData.setRect(x, y, width, height, winheight)
+func (b *Button) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	b.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (b *Button) preferredSize() (width int, height int) {

callbacks_unix.go

@@ -42,9 +42,12 @@ func our_window_configure_event_callback(widget *C.GtkWidget, event *C.GdkEvent,
 	if s.container != nil && s.resize != nil {		// wait for init
 		width, height := gtk_window_get_size(s.widget)
 		// top-left is (0,0) so no need for winheight
-		err := s.resize(0, 0, width, height, 0)
-		if err != nil {
-			panic("child resize failed: " + err.Error())
+		resizeList := s.resize(0, 0, width, height)
+		for _, s := range resizeList {
+			err := s.sysData.setRect(s.x, s.y, s.width, s.height, 0)
+			if err != nil {
+				panic("child resize failed: " + err.Error())
+			}
 		}
 	}
 	// returning false indicates that we continue processing events related to configure-event; if we choose not to, then after some controls have been added, the layout fails completely and everything stays in the starting position/size

checkbox.go

@@ -68,8 +68,14 @@ func (c *Checkbox) make(window *sysData) error {
 	return nil
 }
 
-func (c *Checkbox) setRect(x int, y int, width int, height int, winheight int) error {
-	return c.sysData.setRect(x, y, width, height, winheight)
+func (c *Checkbox) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	c.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (c *Checkbox) preferredSize() (width int, height int) {

combobox.go

@@ -143,8 +143,14 @@ func (c *Combobox) make(window *sysData) (err error) {
 	return nil
 }
 
-func (c *Combobox) setRect(x int, y int, width int, height int, winheight int) error {
-	return c.sysData.setRect(x, y, width, height, winheight)
+func (c *Combobox) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	c.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (c *Combobox) preferredSize() (width int, height int) {

control.go

@@ -9,6 +9,6 @@ import (
 // A Control represents an UI control. Note that Control contains unexported members; this has the consequence that you can't build custom controls that interface directly with the system-specific code (fo rinstance, to import an unsupported control), or at least not without some hackery. If you want to make your own controls, embed Area and provide its necessities.
 type Control interface {
 	make(window *sysData) error
-	setRect(x int, y int, width int, height int, winheight int) error
+	setRect(x int, y int, width int, height int) []resizerequest
 	preferredSize() (width int, height int)
 }

delegate_darwin.go

@@ -90,9 +90,12 @@ func appDelegate_windowDidResize(self C.id, sel C.SEL, notification C.id) {
 	r := C.objc_msgSend_stret_rect_noargs(wincv, _frame)
 	if sysData.resize != nil {
 		// winheight is used here because (0,0) is the bottom-left corner, not the top-left corner
-		err := sysData.resize(int(r.x), int(r.y), int(r.width), int(r.height), int(r.height))
-		if err != nil {
-			panic("child resize failed: " + err.Error())
+		resizeList := sysData.resize(int(r.x), int(r.y), int(r.width), int(r.height))
+		for _, s := range resizeList {
+			err := s.sysData.setRect(s.x, s.y, s.width, s.height, int(r.height))
+			if err != nil {
+				panic("child resize failed: " + err.Error())
+			}
 		}
 	}
 	C.objc_msgSend_noargs(win, _display)		// redraw everything; TODO only if resize() was called?

grid.go

@@ -120,7 +120,7 @@ func (g *Grid) make(window *sysData) error {
 	return nil
 }
 
-func (g *Grid) setRect(x int, y int, width int, height int, winheight int) error {
+func (g *Grid) setRect(x int, y int, width int, height int) (rr []resizerequest) {
 	max := func(a int, b int) int {
 		if a > b {
 			return a
@@ -171,16 +171,13 @@ func (g *Grid) setRect(x int, y int, width int, height int, winheight int) error
 				w = g.colwidths[col]
 				h = g.rowheights[row]
 			}
-			err := c.setRect(x, y, w, h, winheight)
-			if err != nil {
-				return fmt.Errorf("error setting size of control (%d,%d) in Grid.setRect(): %v", row, col, err)
-			}
+			rr = append(rr, c.setRect(x, y, w, h)...)
 			x += g.colwidths[col]
 		}
 		x = startx
 		y += g.rowheights[row]
 	}
-	return nil
+	return rr
 }
 
 // filling and stretchy are ignored for preferred size calculation

label.go

@@ -55,8 +55,14 @@ func (l *Label) make(window *sysData) error {
 	return nil
 }
 
-func (l *Label) setRect(x int, y int, width int, height int, winheight int) error {
-	return l.sysData.setRect(x, y, width, height, winheight)
+func (l *Label) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	l.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (l *Label) preferredSize() (width int, height int) {

lineedit.go

@@ -67,8 +67,14 @@ func (l *LineEdit) make(window *sysData) error {
 	return nil
 }
 
-func (l *LineEdit) setRect(x int, y int, width int, height int, winheight int) error {
-	return l.sysData.setRect(x, y, width, height, winheight)
+func (l *LineEdit) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	l.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (l *LineEdit) preferredSize() (width int, height int) {

listbox.go

@@ -144,8 +144,14 @@ func (l *Listbox) make(window *sysData) (err error) {
 	return nil
 }
 
-func (l *Listbox) setRect(x int, y int, width int, height int, winheight int) error {
-	return l.sysData.setRect(x, y, width, height, winheight)
+func (l *Listbox) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	l.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (l *Listbox) preferredSize() (width int, height int) {

progressbar.go

@@ -55,8 +55,14 @@ func (p *ProgressBar) make(window *sysData) error {
 	return nil
 }
 
-func (p *ProgressBar) setRect(x int, y int, width int, height int, winheight int) error {
-	return p.sysData.setRect(x, y, width, height, winheight)
+func (p *ProgressBar) setRect(x int, y int, width int, height int) []resizerequest {
+	return []resizerequest{resizerequest{
+		sysData:	p.sysData,
+		x:		x,
+		y:		y,
+		width:	width,
+		height:	height,
+	}}
 }
 
 func (p *ProgressBar) preferredSize() (width int, height int) {

stack.go

@@ -77,7 +77,7 @@ func (s *Stack) make(window *sysData) error {
 	return nil
 }
 
-func (s *Stack) setRect(x int, y int, width int, height int, winheight int) error {
+func (s *Stack) setRect(x int, y int, width int, height int) (rr []resizerequest) {
 	var stretchywid, stretchyht int
 
 	if len(s.controls) == 0 {		// do nothing if there's nothing to do
@@ -120,17 +120,14 @@ func (s *Stack) setRect(x int, y int, width int, height int, winheight int) erro
 	}
 	// 3) now actually place controls
 	for i, c := range s.controls {
-		err := c.setRect(x, y, s.width[i], s.height[i], winheight)
-		if err != nil {
-			return fmt.Errorf("error setting size of control %d in Stack.setRect(): %v", i, err)
-		}
+		rr = append(rr, c.setRect(x, y, s.width[i], s.height[i])...)
 		if s.orientation == horizontal {
 			x += s.width[i]
 		} else {
 			y += s.height[i]
 		}
 	}
-	return nil
+	return rr
 }
 
 // The preferred size of a Stack is the sum of the preferred sizes of non-stretchy controls + (the number of stretchy controls * the largest preferred size among all stretchy controls).

stdwndclass_windows.go

@@ -53,9 +53,12 @@ func stdWndProc(s *sysData) func(hwnd _HWND, uMsg uint32, wParam _WPARAM, lParam
 					panic("GetClientRect failed: " + err.Error())
 				}
 				// top-left corner is (0,0) so no need for winheight
-				err = s.resize(int(r.Left), int(r.Top), int(r.Right), int(r.Bottom), 0)
-				if err != nil {
-					panic("child resize failed: " + err.Error())
+				resizeList := s.resize(int(r.Left), int(r.Top), int(r.Right), int(r.Bottom))
+				for _, s := range resizeList {
+					err = s.sysData.setRect(s.x, s.y, s.width, s.height, 0)
+					if err != nil {
+						panic("child resize failed: " + err.Error())
+					}
 				}
 			}
 			return 0

sysdata.go

@@ -17,7 +17,7 @@ func newEvent() chan struct{} {
 type cSysData struct {
 	ctype	int
 	event	chan struct{}
-	resize	func(x int, y int, width int, height int, winheight int) error
+	resize	func(x int, y int, width int, height int) []resizerequest
 	alternate	bool			// editable for Combobox, multi-select for listbox, password for lineedit
 	handler	AreaHandler	// for Areas
 }
@@ -109,3 +109,11 @@ func mksysdata(ctype int) *sysData {
 		},
 	}
 }
+
+type resizerequest struct {
+	sysData	*sysData
+	x		int
+	y		int
+	width	int
+	height	int
+}