Added checkboxes. You can't really do anything with them yet, though...

checkbox.go

@@ -0,0 +1,57 @@
+// 13 february 2014
+//package ui
+package main
+
+import (
+	"sync"
+)
+
+// A Checkbox is a clickable square with a label. The square can be either checked or unchecked.
+type Checkbox struct {
+	// TODO provide a channel for broadcasting check changes
+
+	lock			sync.Mutex
+	created		bool
+	sysData		*sysData
+	initText		string
+	initCheck		bool
+}
+
+// NewCheckbox creates a new checkbox with the specified text.
+func NewCheckbox(text string) (c *Checkbox) {
+	return &Checkbox{
+		sysData:	&sysData{
+			cSysData:		cSysData{
+				ctype:	c_checkbox,
+			},
+		},
+		initText:	text,
+	}
+}
+
+// SetText sets the checkbox's text.
+func (c *Checkbox) SetText(text string) (err error) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	// TODO handle created
+	c.initText = text
+	return nil
+}
+
+// TODO Checked()
+
+func (c *Checkbox) apply(window *sysData) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	return c.sysData.make(c.initText, 300, 300, window)
+	// TODO size to parent size
+}
+
+func (c *Checkbox) setRect(x int, y int, width int, height int) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	return c.sysData.setRect(x, y, width, height)
+}

main.go

@@ -9,6 +9,14 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
+
+	w2 := NewWindow("Checkbox Window", 200, 100)
+	c := NewCheckbox("Check Me")
+	err = w2.Open(c)
+	if err != nil {
+		panic(err)
+	}
+
 mainloop:
 	for {
 		select {

sysdata.go

@@ -30,5 +30,6 @@ func (c *cSysData) setRect(x int, y int, width int, height int) error {
 const (
 	c_window = iota
 	c_button
+	c_checkbox
 	nctypes
 )

sysdata_windows.go

@@ -38,6 +38,11 @@ var classTypes = [nctypes]*classData{
 		style:	_BS_PUSHBUTTON | controlstyle,
 		xstyle:	0 | controlxstyle,
 	},
+	c_checkbox:	&classData{
+		name:	"BUTTON",
+		style:	_BS_AUTOCHECKBOX | controlstyle,
+		xstyle:	0 | controlxstyle,
+	},
 }
 
 func (s *sysData) addChild(child *sysData) _HMENU {