Whoops, forgot to add button.go itself :|

button.go

@@ -0,0 +1,74 @@
+// 12 february 2014
+package main
+
+import (
+	"fmt"
+	"sync"
+)
+
+// A Button represents a clickable button with some text.
+type Button struct {
+	// This channel gets a message when the button is clicked. Unlike other channels in this package, this channel is initialized to non-nil when creating a new button, and cannot be set to nil later.
+	Clicked	chan struct{}
+
+	lock		sync.Mutex
+	created	bool
+	parent	Control
+	pWin		*Window
+	sysData	*sysData
+	initText	string
+}
+
+// NewButton creates a new button with the specified text.
+func NewButton(text string) (b *Button) {
+	return &Button{
+		sysData:	&sysData{
+			cSysData:		cSysData{
+				ctype:	c_button,
+			},
+		},
+		initText:	text,
+		Clicked:	make(chan struct{}),
+	}
+}
+
+// SetText sets the button's text.
+func (b *Button) SetText(text string) (err error) {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	if b.pWin != nil && b.pWin.created {
+		panic("TODO")
+	}
+	b.initText = text
+	return nil
+}
+
+func (b *Button) apply() error {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	if b.pWin == nil {
+		panic(fmt.Sprintf("button (initial text: %q) without parent window", b.initText))
+	}
+	if !b.pWin.created {
+		b.sysData.clicked = b.Clicked
+		b.sysData.parentWindow = b.pWin.sysData
+		return b.sysData.make(b.initText, 300, 300)
+		// TODO size to parent size
+	}
+	return b.sysData.show()
+}
+
+func (b *Button) setParent(c Control) {
+	b.parent = c
+	if w, ok := b.parent.(*Window); ok {
+		b.pWin = w
+	} else {
+		b.pWin = c.parentWindow()
+	}
+}
+
+func (b *Button) parentWindow() *Window {
+	return b.pWin
+}