Set up the absolute basic Spinbox and implemented it on GTK+. This is easy as it's one control on GTK+; now we have to do it on Windows and Mac OS X. And on those platforms, those are two separate controls (a standard edit control and an up-down/NSSpinner).

basicctrls.go

@@ -139,3 +139,21 @@ type Textbox interface {
 func NewTextbox() Textbox {
 	return newTextbox()
 }
+
+// Spinbox is a Control that provides a text entry field that accepts integers and up and down buttons to increment and decrement those values.
+// This control is in its preliminary state.
+// TODO everything:
+// - TODO set increment
+// - TODO set step
+// - TODO set page step?
+// - TODO wrapping
+// - TODO set/get integer value
+// - TODO negative values
+type Spinbox interface {
+	Control
+}
+
+// NewSpinbox creates a new Spinbox.
+func NewSpinbox() Spinbox {
+	return newSpinbox()
+}

spinbox_unix.go

@@ -0,0 +1,30 @@
+// +build !windows,!darwin
+
+// 28 october 2014
+
+package ui
+
+import (
+	"unsafe"
+)
+
+// #include "gtk_unix.h"
+import "C"
+
+// TODO preferred width may be too wide
+
+type spinbox struct {
+	*controlSingleWidget
+	spinbutton	*C.GtkSpinButton
+}
+
+func newSpinbox() Spinbox {
+	widget := C.gtk_spin_button_new_with_range(0, 100, 1)
+	s := &spinbox{
+		controlSingleWidget:	newControlSingleWidget(widget),
+		spinbutton:			(*C.GtkSpinButton)(unsafe.Pointer(widget)),
+	}
+	C.gtk_spin_button_set_digits(s.spinbutton, 0)				// integers
+	C.gtk_spin_button_set_numeric(s.spinbutton, C.TRUE)		// digits only
+	return s
+}

zz_test.go

@@ -149,9 +149,9 @@ func (tw *testwin) addfe() {
 		tw.openbtn, tw.fnlabel)
 	tw.festack.SetStretchy(4)
 	tw.festack.SetStretchy(6)
-	tw.festack2 = newVerticalStack(Space(), NewTextbox())
-	tw.festack2.SetStretchy(0)
+	tw.festack2 = newVerticalStack(NewSpinbox(), Space(), NewTextbox())
 	tw.festack2.SetStretchy(1)
+	tw.festack2.SetStretchy(2)
 	tw.festack = newHorizontalStack(tw.festack, tw.festack2)
 	tw.festack.SetStretchy(0)
 	tw.festack.SetStretchy(1)