diff --git a/AAA_GOFILES/button.go b/AAA_GOFILES/button.go
deleted file mode 100644
index 2696f82..0000000
--- a/AAA_GOFILES/button.go
+++ /dev/null
@@ -1,114 +0,0 @@
-// 12 december 2015
-
-package ui
-
-import (
-	"unsafe"
-)
-
-// #include "ui.h"
-// extern void doButtonOnClicked(uiButton *, void *);
-// static inline void realuiButtonOnClicked(uiButton *b)
-// {
-// 	uiButtonOnClicked(b, doButtonOnClicked, NULL);
-// }
-import "C"
-
-// no need to lock this; only the GUI thread can access it
-var buttons = make(map[*C.uiButton]*Button)
-
-// Button is a Control that represents a button that the user can
-// click to perform an action. A Button has a text label that should
-// describe what the button does.
-type Button struct {
-	c	*C.uiControl
-	b	*C.uiButton
-
-	onClicked		func(*Button)
-}
-
-// NewButton creates a new Button with the given text as its label.
-func NewButton(text string) *Button {
-	b := new(Button)
-
-	ctext := C.CString(text)
-	b.b = C.uiNewButton(ctext)
-	b.c = (*C.uiControl)(unsafe.Pointer(b.b))
-	freestr(ctext)
-
-	C.realuiButtonOnClicked(b.b)
-	buttons[b.b] = b
-
-	return b
-}
-
-// Destroy destroys the Button.
-func (b *Button) Destroy() {
-	delete(buttons, b.b)
-	C.uiControlDestroy(b.c)
-}
-
-// LibuiControl returns the libui uiControl pointer that backs
-// the Button. This is only used by package ui itself and should
-// not be called by programs.
-func (b *Button) LibuiControl() uintptr {
-	return uintptr(unsafe.Pointer(b.c))
-}
-
-// Handle returns the OS-level handle associated with this Button.
-// On Windows this is an HWND of a standard Windows API BUTTON
-// class (as provided by Common Controls version 6).
-// On GTK+ this is a pointer to a GtkButton.
-// On OS X this is a pointer to a NSButton.
-func (b *Button) Handle() uintptr {
-	return uintptr(C.uiControlHandle(b.c))
-}
-
-// Show shows the Button.
-func (b *Button) Show() {
-	C.uiControlShow(b.c)
-}
-
-// Hide hides the Button.
-func (b *Button) Hide() {
-	C.uiControlHide(b.c)
-}
-
-// Enable enables the Button.
-func (b *Button) Enable() {
-	C.uiControlEnable(b.c)
-}
-
-// Disable disables the Button.
-func (b *Button) Disable() {
-	C.uiControlDisable(b.c)
-}
-
-// Text returns the Button's text.
-func (b *Button) Text() string {
-	ctext := C.uiButtonText(b.b)
-	text := C.GoString(ctext)
-	C.uiFreeText(ctext)
-	return text
-}
-
-// SetText sets the Button's text to text.
-func (b *Button) SetText(text string) {
-	ctext := C.CString(text)
-	C.uiButtonSetText(b.b, ctext)
-	freestr(ctext)
-}
-
-// OnClicked registers f to be run when the user clicks the Button.
-// Only one function can be registered at a time.
-func (b *Button) OnClicked(f func(*Button)) {
-	b.onClicked = f
-}
-
-//export doButtonOnClicked
-func doButtonOnClicked(bb *C.uiButton, data unsafe.Pointer) {
-	b := buttons[bb]
-	if b.onClicked != nil {
-		b.onClicked(b)
-	}
-}
diff --git a/AAA_GOFILES/control.go b/AAA_GOFILES/control.go
deleted file mode 100644
index 94ea34f..0000000
--- a/AAA_GOFILES/control.go
+++ /dev/null
@@ -1,107 +0,0 @@
-// 12 december 2015
-
-package ui
-
-import (
-	"unsafe"
-)
-
-// #include "ui.h"
-import "C"
-
-// Control represents a GUI control. It provdes methods
-// common to all Controls.
-// 
-// To create a new Control, implement the control on
-// the libui side, then provide access to that control on
-// the Go side via an implementation of Control as
-// described.
-type Control interface {
-	// Destroy destroys the Control.
-	// 
-	// Implementations should do any necessary cleanup,
-	// then call LibuiControlDestroy.
-	Destroy()
-
-	// LibuiControl returns the libui uiControl pointer that backs
-	// the Control. This is only used by package ui itself and should
-	// not be called by programs.
-	LibuiControl() uintptr
-
-	// Handle returns the OS-level handle that backs the
-	// Control. On OSs that use reference counting for
-	// controls, Handle does not increment the reference
-	// count; you are sharing package ui's reference.
-	// 
-	// Implementations should call LibuiControlHandle and
-	// document exactly what kind of handle is returned.
-	Handle() uintptr
-
-	// Show shows the Control.
-	// 
-	// Implementations should call LibuiControlShow.
-	Show()
-
-	// Hide shows the Control. Hidden controls do not participate
-	// in layout (that is, Box, Grid, etc. does not reserve space for
-	// hidden controls).
-	// 
-	// Implementations should call LibuiControlHide.
-	Hide()
-
-	// Enable enables the Control.
-	// 
-	// Implementations should call LibuiControlEnable.
-	Enable()
-
-	// Disable disables the Control.
-	// 
-	// Implementations should call LibuiControlDisable.
-	Disable()
-}
-
-func touiControl(c uintptr) *C.uiControl {
-	return (*C.uiControl)(unsafe.Pointer(c))
-}
-
-// LibuiControlDestroy allows implementations of Control
-// to call the libui function uiControlDestroy.
-func LibuiControlDestroy(c uintptr) {
-	C.uiControlDestroy(touiControl(c))
-}
-
-// LibuiControlHandle allows implementations of Control
-// to call the libui function uiControlHandle.
-func LibuiControlHandle(c uintptr) uintptr {
-	return uintptr(C.uiControlHandle(touiControl(c)))
-}
-
-// LibuiControlShow allows implementations of Control
-// to call the libui function uiControlShow.
-func LibuiControlShow(c uintptr) {
-	C.uiControlShow(touiControl(c))
-}
-
-// LibuiControlHide allows implementations of Control
-// to call the libui function uiControlHide.
-func LibuiControlHide(c uintptr) {
-	C.uiControlHide(touiControl(c))
-}
-
-// LibuiControlEnable allows implementations of Control
-// to call the libui function uiControlEnable.
-func LibuiControlEnable(c uintptr) {
-	C.uiControlEnable(touiControl(c))
-}
-
-// LibuiControlDisable allows implementations of Control
-// to call the libui function uiControlDisable.
-func LibuiControlDisable(c uintptr) {
-	C.uiControlDisable(touiControl(c))
-}
-
-// LibuiFreeText allows implementations of Control
-// to call the libui function uiFreeText.
-func LibuiFreeText(c uintptr) {
-	C.uiFreeText((*C.char)(unsafe.Pointer(c)))
-}
diff --git a/button.go b/button.go
new file mode 100644
index 0000000..a0c4e67
--- /dev/null
+++ b/button.go
@@ -0,0 +1,63 @@
+// 12 december 2015
+
+package ui
+
+import (
+	"unsafe"
+)
+
+// #include "ui.h"
+// extern void doButtonOnClicked(uiButton *, void *);
+import "C"
+
+// Button is a Control that represents a button that the user can
+// click to perform an action. A Button has a text label that should
+// describe what the button does.
+type Button struct {
+	ControlBase
+	b	*C.uiButton
+	onClicked		func(*Button)
+}
+
+// NewButton creates a new Button with the given text as its label.
+func NewButton(text string) *Button {
+	b := new(Button)
+
+	ctext := C.CString(text)
+	b.b = C.uiNewButton(ctext)
+	freestr(ctext)
+
+	C.uiButtonOnClicked(b.b, C.doButtonOnClicked, nil)
+
+	b.ControlBase = NewControlBase(b, uintptr(unsafe.Pointer(b.b)))
+	return b
+}
+
+// Text returns the Button's text.
+func (b *Button) Text() string {
+	ctext := C.uiButtonText(b.b)
+	text := C.GoString(ctext)
+	C.uiFreeText(ctext)
+	return text
+}
+
+// SetText sets the Button's text to text.
+func (b *Button) SetText(text string) {
+	ctext := C.CString(text)
+	C.uiButtonSetText(b.b, ctext)
+	freestr(ctext)
+}
+
+// OnClicked registers f to be run when the user clicks the Button.
+// Only one function can be registered at a time.
+func (b *Button) OnClicked(f func(*Button)) {
+	b.onClicked = f
+}
+
+//export doButtonOnClicked
+func doButtonOnClicked(bb *C.uiButton, data unsafe.Pointer) {
+	b := ControlFromLibui(uintptr(unsafe.Pointer(bb))).(*Button)
+	if b.onClicked != nil {
+		b.onClicked(b)
+	}
+}
diff --git a/control.go b/control.go
new file mode 100644
index 0000000..3bcdfbe
--- /dev/null
+++ b/control.go
@@ -0,0 +1,132 @@
+// 12 december 2015
+
+package ui
+
+import (
+	"unsafe"
+)
+
+// #include "ui.h"
+import "C"
+
+// no need to lock this; only the GUI thread can access it
+var controls = make(map[*C.uiControl]Control)
+
+// Control represents a GUI control. It provdes methods
+// common to all Controls.
+// 
+// The preferred way to create new Controls is to use
+// ControlBase; see ControlBase below.
+type Control interface {
+	// Destroy destroys the Control.
+	Destroy()
+
+	// Handle returns the OS-level handle that backs the
+	// Control. On OSs that use reference counting for
+	// controls, Handle does not increment the reference
+	// count; you are sharing package ui's reference.
+	Handle() uintptr
+
+	// Visible returns whether the Control is visible.
+	Visible() bool
+
+	// Show shows the Control.
+	Show()
+
+	// Hide shows the Control. Hidden controls do not participate
+	// in layout (that is, Box, Grid, etc. does not reserve space for
+	// hidden controls).
+	Hide()
+
+	// Enabled returns whether the Control is enabled.
+	Enabled() bool
+
+	// Enable enables the Control.
+	Enable()
+
+	// Disable disables the Control.
+	Disable()
+}
+
+// ControlBase is an implementation of Control that provides
+// all the methods that Control requires. To use it, embed a
+// ControlBase (not a *ControlBase) into your structure, then
+// assign the result of NewControlBase to that field:
+// 
+// 	type MyControl struct {
+// 		ui.ControlBase
+// 		c *C.MyControl
+// 	}
+// 	
+// 	func NewMyControl() *MyControl {
+// 		m := &NewMyControl{
+// 			c: C.newMyControl(),
+// 		}
+// 		m.ControlBase = ui.NewControlBase(m, uintptr(unsafe.Pointer(c)))
+// 		return m
+// 	}
+type ControlBase struct {
+	iface		Control
+	c		*C.uiControl
+}
+
+// NewControlBase creates a new ControlBase. See the
+// documentation of ControlBase for an example.
+// NewControl should only be called once per instance of Control.
+func NewControlBase(iface Control, c uintptr) ControlBase {
+	b := ControlBase{
+		iface:	iface,
+		c:		(*C.uiControl)(unsafe.Pointer(c)),
+	}
+	controls[b.c] = b.iface
+	return b
+}
+
+func (c *ControlBase) Destroy() {
+	delete(controls, c.c)
+	C.uiControlDestroy(c.c)
+}
+
+func (c *ControlBase) Handle() uintptr {
+	return uintptr(C.uiControlHandle(c.c))
+}
+
+func (c *ControlBase) Visible() bool {
+	return frombool(C.uiControlVisible(c.c))
+}
+
+func (c *ControlBase) Show() {
+	C.uiControlShow(c.c)
+}
+
+func (c *ControlBase) Hide() {
+	C.uiControlHide(c.c)
+}
+
+func (c *ControlBase) Enabled() bool {
+	return frombool(C.uiControlEnabled(c.c))
+}
+
+func (c *ControlBase) Enable() {
+	C.uiControlEnable(c.c)
+}
+
+func (c *ControlBase) Disable() {
+	C.uiControlDisable(c.c)
+}
+
+// ControlFromLibui returns the Control associated with a libui
+// uiControl. This is intended for implementing event handlers
+// on the Go side, to prevent sharing Go pointers with C.
+// This function only works on Controls that use ControlBase.
+func ControlFromLibui(c uintptr) Control {
+	// comma-ok form to avoid creating nil entries
+	c, _ := controls[(*C.uiControl)(unsafe.Pointer(c))]
+	return c
+}
+
+// LibuiFreeText allows implementations of Control
+// to call the libui function uiFreeText.
+func LibuiFreeText(c uintptr) {
+	C.uiFreeText((*C.char)(unsafe.Pointer(c)))
+}