Added the initial implementaiton of Spinbox on Mac OS X. It doesn't quite work yet.

container_darwin.go

@@ -53,6 +53,7 @@ func containerResized(data unsafe.Pointer) {
 }
 
 // These are based on measurements from Interface Builder.
+// TODO reverify these against /layout rects/, not /frame rects/
 const (
 	macXMargin  = 20
 	macYMargin  = 20

objc_darwin.h

@@ -151,4 +151,8 @@ extern void openFile(id, void *);
 extern id newWarningPopover(char *);
 extern void warningPopoverShow(id, id);
 
+/* spinbox_darwin.m */
+extern id newSpinboxStepper(void);
+extern id spinboxSetup(id, id, void *);
+
 #endif

spinbox_darwin.go

@@ -2,6 +2,10 @@
 
 package ui
 
+import (
+	"unsafe"
+)
+
 // #include "objc_darwin.h"
 import "C"
 
@@ -15,3 +19,46 @@ import "C"
 // - http://andrehoffmann.wordpress.com/tag/nsstepper/ ?
 // TODO
 // - proper spacing between edit and spinner: Interface Builder isn't clear; NSDatePicker doesn't spill the beans
+
+type spinbox struct {
+	textfield		C.id
+	stepper		C.id
+	objcspinbox	C.id
+}
+
+func newSpinbox() Spinbox {
+	s := new(spinbox)
+	s.textfield = C.newTextField()
+	s.stepper = C.newSpinboxStepper()
+	s.objcspinbox = C.spinboxSetup(s.textfield, s.stepper, unsafe.Pointer(s))
+	return s
+}
+
+func (s *spinbox) setParent(p *controlParent) {
+	C.parent(s.textfield, p.id)
+	C.parent(s.stepper, p.id)
+}
+
+func (s *spinbox) preferredSize(d *sizing) (width, height int) {
+	// TODO
+	return 20, 20
+}
+
+func (s *spinbox) resize(x int, y int, width int, height int, d *sizing) {
+	// TODO
+	C.moveControl(s.textfield, C.intptr_t(x), C.intptr_t(y), C.intptr_t(width - 20), C.intptr_t(height))
+	C.moveControl(s.stepper, C.intptr_t(x + width - 15), C.intptr_t(y), C.intptr_t(15), C.intptr_t(height))
+}
+
+func (s *spinbox) nTabStops() int {
+	// TODO does the stepper count?
+	return 1
+}
+
+func (s *spinbox) containerShow() {
+	// only provided for the Windows backend
+}
+
+func (s *spinbox) containerHide() {
+	// only provided for the Windows backend
+}

spinbox_darwin.m

@@ -0,0 +1,40 @@
+// 29 october 2014
+
+#include "objc_darwin.h"
+#include "_cgo_export.h"
+#import <Cocoa/Cocoa.h>
+
+@interface goSpinbox : NSObject {
+@public
+	void *gospinbox;
+}
+@property NSInteger integerValue;
+@end
+
+@implementation goSpinbox
+@synthesize integerValue;
+@end
+
+id newSpinboxStepper(void)
+{
+	NSStepper *s;
+
+	s = [[NSStepper alloc] initWithFrame:NSZeroRect];
+	[s setMinValue:0];
+	[s setMaxValue:100];
+	[s setIncrement:1];
+	[s setAutorepeat:YES];		// hold mouse button to step repeatedly
+	return (id) s;
+}
+
+id spinboxSetup(id textfield, id stepper, void *gospinbox)
+{
+	goSpinbox *g;
+
+	g = [goSpinbox new];
+	g->gospinbox = gospinbox;
+	// TODO set any options?
+	[textfield bind:@"integerValue" toObject:g withKeyPath:@"integerValue" options:nil];
+	[stepper bind:@"integerValue" toObject:g withKeyPath:@"integerValue" options:nil];
+	return (id) g;
+}