diff --git a/app/os.go b/app/os.go
index 75d0e03d..a5f2489d 100644
--- a/app/os.go
+++ b/app/os.go
@@ -6,6 +6,7 @@ package app
 
 import (
 	"errors"
+	"image"
 	"image/color"
 
 	"gioui.org/io/key"
@@ -21,35 +22,76 @@ type size struct {
 	Height unit.Value
 }
 
-type config struct {
-	Size            *size
-	MinSize         *size
-	MaxSize         *size
-	Title           *string
-	WindowMode      *windowMode
-	StatusColor     *color.NRGBA
-	NavigationColor *color.NRGBA
-	Orientation     *orientation
-	CustomRenderer  bool
+// Config describes a Window configuration.
+type Config struct {
+	// Size is the window dimensions (Width, Height).
+	Size image.Point
+	// MaxSize is the window maximum allowed dimensions.
+	MaxSize image.Point
+	// MinSize is the window minimum allowed dimensions.
+	MinSize image.Point
+	// Title is the window title displayed in its decoration bar.
+	Title string
+	// WindowMode is the window mode.
+	Mode WindowMode
+	// StatusColor is the color of the Android status bar.
+	StatusColor color.NRGBA
+	// NavigationColor is the color of the navigation bar
+	// on Android, or the address bar in browsers.
+	NavigationColor color.NRGBA
+	// Orientation is the current window orientation.
+	Orientation Orientation
+	// CustomRenderer is true when the window content is rendered by the
+	// client.
+	CustomRenderer bool
+}
+
+func (c *Config) apply(m unit.Metric, options []Option) {
+	for _, o := range options {
+		o(m, c)
+	}
 }
 
 type wakeupEvent struct{}
 
-type windowMode uint8
+// WindowMode is the window mode (WindowMode.Option sets it).
+//
+// Supported platforms are macOS, X11, Windows, Android and JS.
+type WindowMode uint8
 
 const (
-	windowed windowMode = iota
-	fullscreen
+	// Windowed is the normal window mode with OS specific window decorations.
+	Windowed WindowMode = iota
+	// Fullscreen is the full screen window mode.
+	Fullscreen
 )
 
-type orientation uint8
+func (m WindowMode) Option() Option {
+	return func(_ unit.Metric, cnf *Config) {
+		cnf.Mode = m
+	}
+}
+
+// Orientation is the orientation of the app (Orientation.Option sets it).
+//
+// Supported platforms are Android and JS.
+type Orientation uint8
 
 const (
-	anyOrientation orientation = iota
-	landscapeOrientation
-	portraitOrientation
+	// AnyOrientation allows the window to be freely orientated.
+	AnyOrientation Orientation = iota
+	// LandscapeOrientation constrains the window to landscape orientations.
+	LandscapeOrientation
+	// PortraitOrientation constrains the window to portrait orientations.
+	PortraitOrientation
 )
 
+func (o Orientation) Option() Option {
+	return func(_ unit.Metric, cnf *Config) {
+		cnf.Orientation = o
+	}
+}
+
 type frameEvent struct {
 	system.FrameEvent
 
@@ -91,7 +133,10 @@ type driver interface {
 	WriteClipboard(s string)
 
 	// Configure the window.
-	Configure(cnf *config)
+	Configure([]Option)
+
+	// Config returns the current configuration.
+	Config() Config
 
 	// SetCursor updates the current cursor to name.
 	SetCursor(name pointer.CursorName)
@@ -109,8 +154,8 @@ type windowRendezvous struct {
 }
 
 type windowAndConfig struct {
-	window *callbacks
-	cnf    *config
+	window  *callbacks
+	options []Option
 }
 
 func newWindowRendezvous() *windowRendezvous {
diff --git a/app/os_android.go b/app/os_android.go
index 932c09c5..832e88b0 100644
--- a/app/os_android.go
+++ b/app/os_android.go
@@ -144,7 +144,8 @@ type window struct {
 	started   bool
 	animating bool
 
-	win *C.ANativeWindow
+	win    *C.ANativeWindow
+	config Config
 }
 
 // gioView hold cached JNI methods for GioView.
@@ -337,7 +338,7 @@ func Java_org_gioui_GioView_onCreateView(env *C.JNIEnv, class C.jclass, view C.j
 	handle := C.jlong(view)
 	views[handle] = w
 	w.loadConfig(env, class)
-	w.Configure(wopts.cnf)
+	w.Configure(wopts.options)
 	w.setStage(system.StagePaused)
 	w.callbacks.Event(ViewEvent{View: uintptr(view)})
 	return handle
@@ -762,8 +763,8 @@ func goString(env *C.JNIEnv, str C.jstring) string {
 func osMain() {
 }
 
-func newWindow(window *callbacks, cnf *config) error {
-	mainWindow.in <- windowAndConfig{window, cnf}
+func newWindow(window *callbacks, options []Option) error {
+	mainWindow.in <- windowAndConfig{window, options}
 	return <-mainWindow.errs
 }
 
@@ -787,23 +788,40 @@ func (w *window) ReadClipboard() {
 	})
 }
 
-func (w *window) Configure(cnf *config) {
+func (w *window) Configure(options []Option) {
 	runInJVM(javaVM(), func(env *C.JNIEnv) {
-		if o := cnf.Orientation; o != nil {
-			setOrientation(env, w.view, *o)
+		prev := w.config
+		cnf := w.config
+		cnf.apply(unit.Metric{}, options)
+		if prev.Orientation != cnf.Orientation {
+			w.config.Orientation = cnf.Orientation
+			setOrientation(env, w.view, cnf.Orientation)
 		}
-		if o := cnf.NavigationColor; o != nil {
-			setNavigationColor(env, w.view, *o)
+		if prev.NavigationColor != cnf.NavigationColor {
+			w.config.NavigationColor = cnf.NavigationColor
+			setNavigationColor(env, w.view, cnf.NavigationColor)
 		}
-		if o := cnf.StatusColor; o != nil {
-			setStatusColor(env, w.view, *o)
+		if prev.StatusColor != cnf.StatusColor {
+			w.config.StatusColor = cnf.StatusColor
+			setStatusColor(env, w.view, cnf.StatusColor)
 		}
-		if o := cnf.WindowMode; o != nil {
-			setWindowMode(env, w.view, *o)
+		if prev.Mode != cnf.Mode {
+			switch cnf.Mode {
+			case Fullscreen:
+				callVoidMethod(env, w.view, gioView.setFullscreen, C.JNI_TRUE)
+				w.config.Mode = Fullscreen
+			case Windowed:
+				callVoidMethod(env, w.view, gioView.setFullscreen, C.JNI_FALSE)
+				w.config.Mode = Windowed
+			}
 		}
 	})
 }
 
+func (w *window) Config() Config {
+	return w.config
+}
+
 func (w *window) SetCursor(name pointer.CursorName) {
 	runInJVM(javaVM(), func(env *C.JNIEnv) {
 		setCursor(env, w.view, name)
@@ -839,18 +857,18 @@ func setCursor(env *C.JNIEnv, view C.jobject, name pointer.CursorName) {
 	callVoidMethod(env, view, gioView.setCursor, jvalue(curID))
 }
 
-func setOrientation(env *C.JNIEnv, view C.jobject, mode orientation) {
+func setOrientation(env *C.JNIEnv, view C.jobject, mode Orientation) {
 	var (
 		id         int
 		idFallback int // Used only for SDK 17 or older.
 	)
 	// Constants defined at https://developer.android.com/reference/android/content/pm/ActivityInfo.
 	switch mode {
-	case anyOrientation:
+	case AnyOrientation:
 		id, idFallback = 2, 2 // SCREEN_ORIENTATION_USER
-	case landscapeOrientation:
+	case LandscapeOrientation:
 		id, idFallback = 11, 0 // SCREEN_ORIENTATION_USER_LANDSCAPE (or SCREEN_ORIENTATION_LANDSCAPE)
-	case portraitOrientation:
+	case PortraitOrientation:
 		id, idFallback = 12, 1 // SCREEN_ORIENTATION_USER_PORTRAIT (or SCREEN_ORIENTATION_PORTRAIT)
 	}
 	callVoidMethod(env, view, gioView.setOrientation, jvalue(id), jvalue(idFallback))
@@ -870,15 +888,6 @@ func setNavigationColor(env *C.JNIEnv, view C.jobject, color color.NRGBA) {
 	)
 }
 
-func setWindowMode(env *C.JNIEnv, view C.jobject, mode windowMode) {
-	switch mode {
-	case fullscreen:
-		callVoidMethod(env, view, gioView.setFullscreen, C.JNI_TRUE)
-	default:
-		callVoidMethod(env, view, gioView.setFullscreen, C.JNI_FALSE)
-	}
-}
-
 // Close the window. Not implemented for Android.
 func (w *window) Close() {}
 
diff --git a/app/os_ios.go b/app/os_ios.go
index a6a2bb3e..ab1589f3 100644
--- a/app/os_ios.go
+++ b/app/os_ios.go
@@ -95,6 +95,7 @@ type window struct {
 
 	visible bool
 	cursor  pointer.CursorName
+	config  Config
 
 	pointerMap []C.CFTypeRef
 }
@@ -268,7 +269,11 @@ func (w *window) WriteClipboard(s string) {
 	C.writeClipboard(chars, C.NSUInteger(len(u16)))
 }
 
-func (w *window) Configure(cnf *config) {}
+func (w *window) Configure([]Option) {}
+
+func (w *window) Config() Config {
+	return w.config
+}
 
 func (w *window) SetAnimating(anim bool) {
 	v := w.view
@@ -329,8 +334,8 @@ func (w *window) SetInputHint(_ key.InputHint) {}
 // Close the window. Not implemented for iOS.
 func (w *window) Close() {}
 
-func newWindow(win *callbacks, cnf *config) error {
-	mainWindow.in <- windowAndConfig{win, cnf}
+func newWindow(win *callbacks, options []Option) error {
+	mainWindow.in <- windowAndConfig{win, options}
 	return <-mainWindow.errs
 }
 
diff --git a/app/os_js.go b/app/os_js.go
index 64aa7b1c..61b2948a 100644
--- a/app/os_js.go
+++ b/app/os_js.go
@@ -46,7 +46,7 @@ type window struct {
 	chanAnimation chan struct{}
 	chanRedraw    chan struct{}
 
-	size      f32.Point
+	config    Config
 	inset     f32.Point
 	scale     float32
 	animating bool
@@ -56,7 +56,7 @@ type window struct {
 	wakeups       chan struct{}
 }
 
-func newWindow(win *callbacks, cnf *config) error {
+func newWindow(win *callbacks, options []Option) error {
 	doc := js.Global().Get("document")
 	cont := getContainer(doc)
 	cnv := createCanvas(doc)
@@ -94,7 +94,7 @@ func newWindow(win *callbacks, cnf *config) error {
 	})
 	w.addEventListeners()
 	w.addHistory()
-	w.Configure(cnf)
+	w.Configure(options)
 	w.w = win
 
 	go func() {
@@ -509,21 +509,31 @@ func (w *window) WriteClipboard(s string) {
 	w.clipboard.Call("writeText", s)
 }
 
-func (w *window) Configure(cnf *config) {
-	if o := cnf.Title; o != nil {
-		w.document.Set("title", *o)
+func (w *window) Configure(options []Option) {
+	prev := w.config
+	cnf := w.config
+	cnf.apply(unit.Metric{}, options)
+	if prev.Title != cnf.Title {
+		w.config.Title = cnf.Title
+		w.document.Set("title", cnf.Title)
 	}
-	if o := cnf.WindowMode; o != nil {
-		w.windowMode(*o)
+	if prev.Mode != cnf.Mode {
+		w.windowMode(cnf.Mode)
 	}
-	if o := cnf.NavigationColor; o != nil {
-		w.navigationColor(*o)
+	if prev.NavigationColor != cnf.NavigationColor {
+		w.config.NavigationColor = cnf.NavigationColor
+		w.navigationColor(cnf.NavigationColor)
 	}
-	if o := cnf.Orientation; o != nil {
-		w.orientation(*o)
+	if prev.Orientation != cnf.Orientation {
+		w.config.Orientation = cnf.Orientation
+		w.orientation(cnf.Orientation)
 	}
 }
 
+func (w *window) Config() Config {
+	return w.config
+}
+
 func (w *window) SetCursor(name pointer.CursorName) {
 	style := w.cnv.Get("style")
 	style.Set("cursor", string(name))
@@ -559,24 +569,24 @@ func (w *window) resize() {
 	w.scale = float32(w.window.Get("devicePixelRatio").Float())
 
 	rect := w.cnv.Call("getBoundingClientRect")
-	w.size.X = float32(rect.Get("width").Float()) * w.scale
-	w.size.Y = float32(rect.Get("height").Float()) * w.scale
+	w.config.Size.X = int(rect.Get("width").Float()) * int(w.scale)
+	w.config.Size.Y = int(rect.Get("height").Float()) * int(w.scale)
 
 	if vx, vy := w.visualViewport.Get("width"), w.visualViewport.Get("height"); !vx.IsUndefined() && !vy.IsUndefined() {
-		w.inset.X = w.size.X - float32(vx.Float())*w.scale
-		w.inset.Y = w.size.Y - float32(vy.Float())*w.scale
+		w.inset.X = float32(w.config.Size.X) - float32(vx.Float())*w.scale
+		w.inset.Y = float32(w.config.Size.Y) - float32(vy.Float())*w.scale
 	}
 
-	if w.size.X == 0 || w.size.Y == 0 {
+	if w.config.Size.X == 0 || w.config.Size.Y == 0 {
 		return
 	}
 
-	w.cnv.Set("width", int(w.size.X+.5))
-	w.cnv.Set("height", int(w.size.Y+.5))
+	w.cnv.Set("width", w.config.Size.X)
+	w.cnv.Set("height", w.config.Size.Y)
 }
 
 func (w *window) draw(sync bool) {
-	width, height, insets, metric := w.config()
+	width, height, insets, metric := w.getConfig()
 	if metric == (unit.Metric{}) || width == 0 || height == 0 {
 		return
 	}
@@ -595,8 +605,8 @@ func (w *window) draw(sync bool) {
 	})
 }
 
-func (w *window) config() (int, int, system.Insets, unit.Metric) {
-	return int(w.size.X + .5), int(w.size.Y + .5), system.Insets{
+func (w *window) getConfig() (int, int, system.Insets, unit.Metric) {
+	return w.config.Size.X, w.config.Size.Y, system.Insets{
 			Bottom: unit.Px(w.inset.Y),
 			Right:  unit.Px(w.inset.X),
 		}, unit.Metric{
@@ -605,9 +615,9 @@ func (w *window) config() (int, int, system.Insets, unit.Metric) {
 		}
 }
 
-func (w *window) windowMode(mode windowMode) {
+func (w *window) windowMode(mode WindowMode) {
 	switch mode {
-	case windowed:
+	case Windowed:
 		if !w.document.Get("fullscreenElement").Truthy() {
 			return // Browser is already Windowed.
 		}
@@ -615,26 +625,28 @@ func (w *window) windowMode(mode windowMode) {
 			return // Browser doesn't support such feature.
 		}
 		w.document.Call("exitFullscreen")
-	case fullscreen:
+		w.config.Mode = Windowed
+	case Fullscreen:
 		elem := w.document.Get("documentElement")
 		if !elem.Get("requestFullscreen").Truthy() {
 			return // Browser doesn't support such feature.
 		}
 		elem.Call("requestFullscreen")
+		w.config.Mode = Fullscreen
 	}
 }
 
-func (w *window) orientation(mode orientation) {
+func (w *window) orientation(mode Orientation) {
 	if j := w.screenOrientation; !j.Truthy() || !j.Get("unlock").Truthy() || !j.Get("lock").Truthy() {
 		return // Browser don't support Screen Orientation API.
 	}
 
 	switch mode {
-	case anyOrientation:
+	case AnyOrientation:
 		w.screenOrientation.Call("unlock")
-	case landscapeOrientation:
+	case LandscapeOrientation:
 		w.screenOrientation.Call("lock", "landscape").Call("then", w.redraw)
-	case portraitOrientation:
+	case PortraitOrientation:
 		w.screenOrientation.Call("lock", "portrait").Call("then", w.redraw)
 	}
 }
diff --git a/app/os_macos.go b/app/os_macos.go
index b9e4893e..a80e8a5b 100644
--- a/app/os_macos.go
+++ b/app/os_macos.go
@@ -152,8 +152,8 @@ type window struct {
 	displayLink *displayLink
 	cursor      pointer.CursorName
 
-	scale float32
-	mode  windowMode
+	scale  float32
+	config Config
 }
 
 // viewMap is the mapping from Cocoa NSViews to Go windows.
@@ -210,50 +210,46 @@ func (w *window) WriteClipboard(s string) {
 	C.writeClipboard(chars, C.NSUInteger(len(u16)))
 }
 
-func (w *window) Configure(cnf *config) {
+func (w *window) Configure(options []Option) {
 	screenScale := float32(C.getScreenBackingScale())
 	cfg := configFor(screenScale)
-	val := func(v unit.Value) float32 {
-		return float32(cfg.Px(v)) / screenScale
+	prev := w.config
+	cnf := w.config
+	cnf.apply(cfg, options)
+	cnf.Size = cnf.Size.Div(int(screenScale))
+	cnf.MinSize = cnf.MinSize.Div(int(screenScale))
+	cnf.MaxSize = cnf.MaxSize.Div(int(screenScale))
+
+	if prev.Size != cnf.Size {
+		w.config.Size = cnf.Size
+		C.setSize(w.window, C.CGFloat(cnf.Size.X), C.CGFloat(cnf.Size.Y))
 	}
-	if o := cnf.Size; o != nil {
-		width := val(o.Width)
-		height := val(o.Height)
-		if width > 0 || height > 0 {
-			C.setSize(w.window, C.CGFloat(width), C.CGFloat(height))
-		}
+	if prev.MinSize != cnf.MinSize {
+		w.config.MinSize = cnf.MinSize
+		C.setMinSize(w.window, C.CGFloat(cnf.MinSize.X), C.CGFloat(cnf.MinSize.Y))
 	}
-	if o := cnf.MinSize; o != nil {
-		width := val(o.Width)
-		height := val(o.Height)
-		if width > 0 || height > 0 {
-			C.setMinSize(w.window, C.CGFloat(width), C.CGFloat(height))
-		}
+	if prev.MaxSize != cnf.MaxSize {
+		w.config.MaxSize = cnf.MaxSize
+		C.setMaxSize(w.window, C.CGFloat(cnf.MaxSize.X), C.CGFloat(cnf.MaxSize.Y))
 	}
-	if o := cnf.MaxSize; o != nil {
-		width := val(o.Width)
-		height := val(o.Height)
-		if width > 0 || height > 0 {
-			C.setMaxSize(w.window, C.CGFloat(width), C.CGFloat(height))
-		}
-	}
-	if o := cnf.Title; o != nil {
-		title := C.CString(*o)
+
+	if prev.Title != cnf.Title {
+		w.config.Title = cnf.Title
+		title := C.CString(cnf.Title)
 		defer C.free(unsafe.Pointer(title))
 		C.setTitle(w.window, title)
 	}
-	if o := cnf.WindowMode; o != nil {
-		w.SetWindowMode(*o)
+	if prev.Mode != cnf.Mode {
+		switch cnf.Mode {
+		case Windowed, Fullscreen:
+			w.config.Mode = cnf.Mode
+			C.toggleFullScreen(w.window)
+		}
 	}
 }
 
-func (w *window) SetWindowMode(mode windowMode) {
-	switch mode {
-	case w.mode:
-	case windowed, fullscreen:
-		C.toggleFullScreen(w.window)
-		w.mode = mode
-	}
+func (w *window) Config() Config {
+	return w.config
 }
 
 func (w *window) SetCursor(name pointer.CursorName) {
@@ -455,7 +451,7 @@ func gio_onFinishLaunching() {
 	close(launched)
 }
 
-func newWindow(win *callbacks, cnf *config) error {
+func newWindow(win *callbacks, options []Option) error {
 	<-launched
 	errch := make(chan error)
 	runOnMain(func() {
@@ -468,7 +464,7 @@ func newWindow(win *callbacks, cnf *config) error {
 		w.w = win
 		w.window = C.gio_createWindow(w.view, nil, 0, 0, 0, 0, 0, 0)
 		win.SetDriver(w)
-		w.Configure(cnf)
+		w.Configure(options)
 		if nextTopLeft.x == 0 && nextTopLeft.y == 0 {
 			// cascadeTopLeftFromPoint treats (0, 0) as a no-op,
 			// and just returns the offset we need for the first window.
diff --git a/app/os_unix.go b/app/os_unix.go
index 518f912c..ee831b30 100644
--- a/app/os_unix.go
+++ b/app/os_unix.go
@@ -21,19 +21,19 @@ func osMain() {
 	select {}
 }
 
-type windowDriver func(*callbacks, *config) error
+type windowDriver func(*callbacks, []Option) error
 
 // Instead of creating files with build tags for each combination of wayland +/- x11
 // let each driver initialize these variables with their own version of createWindow.
 var wlDriver, x11Driver windowDriver
 
-func newWindow(window *callbacks, cnf *config) error {
+func newWindow(window *callbacks, options []Option) error {
 	var errFirst error
 	for _, d := range []windowDriver{x11Driver, wlDriver} {
 		if d == nil {
 			continue
 		}
-		err := d(window, cnf)
+		err := d(window, options)
 		if err == nil {
 			return nil
 		}
diff --git a/app/os_wayland.go b/app/os_wayland.go
index 0f857ea1..8ab930cb 100644
--- a/app/os_wayland.go
+++ b/app/os_wayland.go
@@ -185,10 +185,9 @@ type window struct {
 	needAck   bool
 	// The most recent configure serial waiting to be ack'ed.
 	serial   C.uint32_t
-	width    int
-	height   int
 	newScale bool
 	scale    int
+	config   Config
 
 	wakeups chan struct{}
 }
@@ -223,12 +222,12 @@ func init() {
 	wlDriver = newWLWindow
 }
 
-func newWLWindow(window *callbacks, cnf *config) error {
+func newWLWindow(window *callbacks, options []Option) error {
 	d, err := newWLDisplay()
 	if err != nil {
 		return err
 	}
-	w, err := d.createNativeWindow(cnf)
+	w, err := d.createNativeWindow(options)
 	if err != nil {
 		d.destroy()
 		return err
@@ -290,7 +289,7 @@ func (d *wlDisplay) readClipboard() (io.ReadCloser, error) {
 	return r, nil
 }
 
-func (d *wlDisplay) createNativeWindow(cnf *config) (*window, error) {
+func (d *wlDisplay) createNativeWindow(options []Option) (*window, error) {
 	if d.compositor == nil {
 		return nil, errors.New("wayland: no compositor available")
 	}
@@ -357,7 +356,7 @@ func (d *wlDisplay) createNativeWindow(cnf *config) (*window, error) {
 	C.xdg_surface_add_listener(w.wmSurf, &C.gio_xdg_surface_listener, unsafe.Pointer(w.surf))
 	C.xdg_toplevel_add_listener(w.topLvl, &C.gio_xdg_toplevel_listener, unsafe.Pointer(w.surf))
 
-	w.Configure(cnf)
+	w.Configure(options)
 
 	if d.decor != nil {
 		// Request server side decorations.
@@ -488,8 +487,8 @@ func gio_onToplevelClose(data unsafe.Pointer, topLvl *C.struct_xdg_toplevel) {
 func gio_onToplevelConfigure(data unsafe.Pointer, topLvl *C.struct_xdg_toplevel, width, height C.int32_t, states *C.struct_wl_array) {
 	w := callbackLoad(data).(*window)
 	if width != 0 && height != 0 {
-		w.width = int(width)
-		w.height = int(height)
+		w.config.Size.X = int(width)
+		w.config.Size.Y = int(height)
 		w.updateOpaqueRegion()
 	}
 }
@@ -856,7 +855,7 @@ func (w *window) flushFling() {
 	w.fling.xExtrapolation = fling.Extrapolation{}
 	w.fling.yExtrapolation = fling.Extrapolation{}
 	vel := float32(math.Sqrt(float64(estx.Velocity*estx.Velocity + esty.Velocity*esty.Velocity)))
-	_, _, c := w.config()
+	_, _, c := w.getConfig()
 	if !w.fling.anim.Start(c, time.Now(), vel) {
 		return
 	}
@@ -908,19 +907,26 @@ func (w *window) WriteClipboard(s string) {
 	w.disp.writeClipboard([]byte(s))
 }
 
-func (w *window) Configure(cnf *config) {
-	_, _, cfg := w.config()
-	if o := cnf.Size; o != nil {
-		w.width = cfg.Px(o.Width)
-		w.height = cfg.Px(o.Height)
+func (w *window) Configure(options []Option) {
+	_, _, cfg := w.getConfig()
+	prev := w.config
+	cnf := w.config
+	cnf.apply(cfg, options)
+	if prev.Size != cnf.Size {
+		w.config.Size = cnf.Size
 	}
-	if o := cnf.Title; o != nil {
-		title := C.CString(*o)
+	if prev.Title != cnf.Title {
+		w.config.Title = cnf.Title
+		title := C.CString(cnf.Title)
 		C.xdg_toplevel_set_title(w.topLvl, title)
 		C.free(unsafe.Pointer(title))
 	}
 }
 
+func (w *window) Config() Config {
+	return w.config
+}
+
 func (w *window) SetCursor(name pointer.CursorName) {
 	if name == pointer.CursorNone {
 		C.wl_pointer_set_cursor(w.disp.seat.pointer, w.serial, nil, 0, 0)
@@ -1366,7 +1372,7 @@ func (w *window) onPointerMotion(x, y C.wl_fixed_t, t C.uint32_t) {
 
 func (w *window) updateOpaqueRegion() {
 	reg := C.wl_compositor_create_region(w.disp.compositor)
-	C.wl_region_add(reg, 0, 0, C.int32_t(w.width), C.int32_t(w.height))
+	C.wl_region_add(reg, 0, 0, C.int32_t(w.config.Size.X), C.int32_t(w.config.Size.Y))
 	C.wl_surface_set_opaque_region(w.surf, reg)
 	C.wl_region_destroy(reg)
 }
@@ -1396,8 +1402,8 @@ func (w *window) updateOutputs() {
 	}
 }
 
-func (w *window) config() (int, int, unit.Metric) {
-	width, height := w.width*w.scale, w.height*w.scale
+func (w *window) getConfig() (int, int, unit.Metric) {
+	width, height := w.config.Size.X*w.scale, w.config.Size.Y*w.scale
 	return width, height, unit.Metric{
 		PxPerDp: w.ppdp * float32(w.scale),
 		PxPerSp: w.ppsp * float32(w.scale),
@@ -1411,7 +1417,7 @@ func (w *window) draw(sync bool) {
 	if dead || (!anim && !sync) {
 		return
 	}
-	width, height, cfg := w.config()
+	width, height, cfg := w.getConfig()
 	if cfg == (unit.Metric{}) {
 		return
 	}
@@ -1450,7 +1456,7 @@ func (w *window) surface() (*C.struct_wl_surface, int, int) {
 		C.xdg_surface_ack_configure(w.wmSurf, w.serial)
 		w.needAck = false
 	}
-	width, height, scale := w.width, w.height, w.scale
+	width, height, scale := w.config.Size.X, w.config.Size.Y, w.scale
 	if w.newScale {
 		C.wl_surface_set_buffer_scale(w.surf, C.int32_t(scale))
 		w.newScale = false
diff --git a/app/os_windows.go b/app/os_windows.go
index 46b1acb0..640d7321 100644
--- a/app/os_windows.go
+++ b/app/os_windows.go
@@ -32,11 +32,6 @@ type ViewEvent struct {
 	HWND uintptr
 }
 
-type winConstraints struct {
-	minWidth, minHeight int32
-	maxWidth, maxHeight int32
-}
-
 type winDeltas struct {
 	width  int32
 	height int32
@@ -46,8 +41,6 @@ type window struct {
 	hwnd        syscall.Handle
 	hdc         syscall.Handle
 	w           *callbacks
-	width       int
-	height      int
 	stage       system.Stage
 	pointerBtns pointer.Buttons
 
@@ -61,9 +54,8 @@ type window struct {
 
 	animating bool
 
-	minmax winConstraints
 	deltas winDeltas
-	cnf    *config
+	config Config
 }
 
 const _WM_WAKEUP = windows.WM_USER + iota
@@ -96,7 +88,7 @@ func osMain() {
 	select {}
 }
 
-func newWindow(window *callbacks, cnf *config) error {
+func newWindow(window *callbacks, options []Option) error {
 	cerr := make(chan error)
 	go func() {
 		// GetMessage and PeekMessage can filter on a window HWND, but
@@ -104,7 +96,7 @@ func newWindow(window *callbacks, cnf *config) error {
 		// Instead lock the thread so window messages arrive through
 		// unfiltered GetMessage calls.
 		runtime.LockOSThread()
-		w, err := createNativeWindow(cnf)
+		w, err := createNativeWindow()
 		if err != nil {
 			cerr <- err
 			return
@@ -115,7 +107,7 @@ func newWindow(window *callbacks, cnf *config) error {
 		w.w = window
 		w.w.SetDriver(w)
 		w.w.Event(ViewEvent{HWND: uintptr(w.hwnd)})
-		w.Configure(cnf)
+		w.Configure(options)
 		windows.ShowWindow(w.hwnd, windows.SW_SHOWDEFAULT)
 		windows.SetForegroundWindow(w.hwnd)
 		windows.SetFocus(w.hwnd)
@@ -159,20 +151,7 @@ func initResources() error {
 	return nil
 }
 
-func getWindowConstraints(cfg unit.Metric, cnf *config) winConstraints {
-	var minmax winConstraints
-	if o := cnf.MinSize; o != nil {
-		minmax.minWidth = int32(cfg.Px(o.Width))
-		minmax.minHeight = int32(cfg.Px(o.Height))
-	}
-	if o := cnf.MaxSize; o != nil {
-		minmax.maxWidth = int32(cfg.Px(o.Width))
-		minmax.maxHeight = int32(cfg.Px(o.Height))
-	}
-	return minmax
-}
-
-func createNativeWindow(cnf *config) (*window, error) {
+func createNativeWindow() (*window, error) {
 	var resErr error
 	resources.once.Do(func() {
 		resErr = initResources()
@@ -180,8 +159,6 @@ func createNativeWindow(cnf *config) (*window, error) {
 	if resErr != nil {
 		return nil, resErr
 	}
-	dpi := windows.GetSystemDPI()
-	cfg := configForDPI(dpi)
 	dwStyle := uint32(windows.WS_OVERLAPPEDWINDOW)
 	dwExStyle := uint32(windows.WS_EX_APPWINDOW | windows.WS_EX_WINDOWEDGE)
 
@@ -199,9 +176,7 @@ func createNativeWindow(cnf *config) (*window, error) {
 		return nil, err
 	}
 	w := &window{
-		hwnd:   hwnd,
-		minmax: getWindowConstraints(cfg, cnf),
-		cnf:    cnf,
+		hwnd: hwnd,
 	}
 	w.hdc, err = windows.GetDC(hwnd)
 	if err != nil {
@@ -311,16 +286,16 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		}
 	case windows.WM_GETMINMAXINFO:
 		mm := (*windows.MinMaxInfo)(unsafe.Pointer(uintptr(lParam)))
-		if w.minmax.minWidth > 0 || w.minmax.minHeight > 0 {
+		if p := w.config.MinSize; p.X > 0 || p.Y > 0 {
 			mm.PtMinTrackSize = windows.Point{
-				X: w.minmax.minWidth + w.deltas.width,
-				Y: w.minmax.minHeight + w.deltas.height,
+				X: int32(p.X) + w.deltas.width,
+				Y: int32(p.Y) + w.deltas.height,
 			}
 		}
-		if w.minmax.maxWidth > 0 || w.minmax.maxHeight > 0 {
+		if p := w.config.MaxSize; p.X > 0 || p.Y > 0 {
 			mm.PtMaxTrackSize = windows.Point{
-				X: w.minmax.maxWidth + w.deltas.width,
-				Y: w.minmax.maxHeight + w.deltas.height,
+				X: int32(p.X) + w.deltas.width,
+				Y: int32(p.Y) + w.deltas.height,
 			}
 		}
 	case windows.WM_SETCURSOR:
@@ -453,20 +428,19 @@ func (w *window) setStage(s system.Stage) {
 func (w *window) draw(sync bool) {
 	var r windows.Rect
 	windows.GetClientRect(w.hwnd, &r)
-	w.width = int(r.Right - r.Left)
-	w.height = int(r.Bottom - r.Top)
-	if w.width == 0 || w.height == 0 {
+	w.config.Size.X = int(r.Right - r.Left)
+	w.config.Size.Y = int(r.Bottom - r.Top)
+	if w.config.Size.X == 0 || w.config.Size.Y == 0 {
 		return
 	}
 	dpi := windows.GetWindowDPI(w.hwnd)
 	cfg := configForDPI(dpi)
-	w.minmax = getWindowConstraints(cfg, w.cnf)
 	w.w.Event(frameEvent{
 		FrameEvent: system.FrameEvent{
 			Now: time.Now(),
 			Size: image.Point{
-				X: w.width,
-				Y: w.height,
+				X: w.config.Size.X,
+				Y: w.config.Size.Y,
 			},
 			Metric: cfg,
 		},
@@ -515,13 +489,17 @@ func (w *window) readClipboard() error {
 	return nil
 }
 
-func (w *window) Configure(cnf *config) {
-	w.cnf = cnf
-	if o := cnf.Size; o != nil {
-		dpi := windows.GetSystemDPI()
-		cfg := configForDPI(dpi)
-		width := int32(cfg.Px(o.Width))
-		height := int32(cfg.Px(o.Height))
+func (w *window) Configure(options []Option) {
+	dpi := windows.GetSystemDPI()
+	cfg := configForDPI(dpi)
+	prev := w.config
+	cnf := w.config
+	cnf.apply(cfg, options)
+
+	if prev.Size != cnf.Size {
+		width := int32(cnf.Size.X)
+		height := int32(cnf.Size.Y)
+		w.config.Size = cnf.Size
 
 		// Include the window decorations.
 		wr := windows.Rect{
@@ -538,30 +516,35 @@ func (w *window) Configure(cnf *config) {
 		w.deltas.width = width - dw
 		w.deltas.height = height - dh
 
-		w.cnf.Size = o
 		windows.MoveWindow(w.hwnd, 0, 0, width, height, true)
 	}
-	if o := cnf.MinSize; o != nil {
-		w.cnf.MinSize = o
+	if prev.MinSize != cnf.MinSize {
+		w.config.MinSize = cnf.MinSize
 	}
-	if o := cnf.MaxSize; o != nil {
-		w.cnf.MaxSize = o
+	if prev.MaxSize != cnf.MaxSize {
+		w.config.MaxSize = cnf.MaxSize
 	}
-	if o := cnf.Title; o != nil {
-		windows.SetWindowText(w.hwnd, *cnf.Title)
+	if prev.Title != cnf.Title {
+		w.config.Title = cnf.Title
+		windows.SetWindowText(w.hwnd, cnf.Title)
 	}
-	if o := cnf.WindowMode; o != nil {
-		w.SetWindowMode(*o)
+	if prev.Mode != cnf.Mode {
+		w.SetWindowMode(cnf.Mode)
 	}
 }
 
-func (w *window) SetWindowMode(mode windowMode) {
+func (w *window) Config() Config {
+	return w.config
+}
+
+func (w *window) SetWindowMode(mode WindowMode) {
 	// https://devblogs.microsoft.com/oldnewthing/20100412-00/?p=14353
 	switch mode {
-	case windowed:
+	case Windowed:
 		if w.placement == nil {
 			return
 		}
+		w.config.Mode = Windowed
 		windows.SetWindowPlacement(w.hwnd, w.placement)
 		w.placement = nil
 		style := windows.GetWindowLong(w.hwnd)
@@ -570,10 +553,11 @@ func (w *window) SetWindowMode(mode windowMode) {
 			0, 0, 0, 0,
 			windows.SWP_NOOWNERZORDER|windows.SWP_FRAMECHANGED,
 		)
-	case fullscreen:
+	case Fullscreen:
 		if w.placement != nil {
 			return
 		}
+		w.config.Mode = Fullscreen
 		w.placement = windows.GetWindowPlacement(w.hwnd)
 		style := windows.GetWindowLong(w.hwnd)
 		windows.SetWindowLong(w.hwnd, windows.GWL_STYLE, style&^windows.WS_OVERLAPPEDWINDOW)
@@ -672,7 +656,7 @@ func (w *window) HDC() syscall.Handle {
 }
 
 func (w *window) HWND() (syscall.Handle, int, int) {
-	return w.hwnd, w.width, w.height
+	return w.hwnd, w.config.Size.X, w.config.Size.Y
 }
 
 func (w *window) Close() {
diff --git a/app/os_x11.go b/app/os_x11.go
index 0e55b796..a7b6e469 100644
--- a/app/os_x11.go
+++ b/app/os_x11.go
@@ -81,9 +81,7 @@ type x11Window struct {
 		wmStateFullscreen C.Atom
 	}
 	stage  system.Stage
-	cfg    unit.Metric
-	width  int
-	height int
+	metric unit.Metric
 	notify struct {
 		read, write int
 	}
@@ -97,7 +95,7 @@ type x11Window struct {
 		content []byte
 	}
 	cursor pointer.CursorName
-	mode   windowMode
+	config Config
 
 	wakeups chan struct{}
 }
@@ -116,48 +114,57 @@ func (w *x11Window) WriteClipboard(s string) {
 	C.XSetSelectionOwner(w.x, w.atoms.clipboard, w.xw, C.CurrentTime)
 }
 
-func (w *x11Window) Configure(cnf *config) {
+func (w *x11Window) Configure(options []Option) {
 	var shints C.XSizeHints
-	if o := cnf.MinSize; o != nil {
-		shints.min_width = C.int(w.cfg.Px(o.Width))
-		shints.min_height = C.int(w.cfg.Px(o.Height))
+	prev := w.config
+	cnf := w.config
+	cnf.apply(w.metric, options)
+	if prev.MinSize != cnf.MinSize {
+		w.config.MinSize = cnf.MinSize
+		shints.min_width = C.int(cnf.MinSize.X)
+		shints.min_height = C.int(cnf.MinSize.Y)
 		shints.flags = C.PMinSize
 	}
-	if o := cnf.MaxSize; o != nil {
-		shints.max_width = C.int(w.cfg.Px(o.Width))
-		shints.max_height = C.int(w.cfg.Px(o.Height))
+	if prev.MaxSize != cnf.MaxSize {
+		w.config.MaxSize = cnf.MaxSize
+		shints.max_width = C.int(cnf.MaxSize.X)
+		shints.max_height = C.int(cnf.MaxSize.Y)
 		shints.flags = shints.flags | C.PMaxSize
 	}
 	if shints.flags != 0 {
 		C.XSetWMNormalHints(w.x, w.xw, &shints)
 	}
 
-	if o := cnf.Size; o != nil {
-		C.XResizeWindow(w.x, w.xw, C.uint(w.cfg.Px(o.Width)), C.uint(w.cfg.Px(o.Height)))
+	if prev.Size != cnf.Size {
+		w.config.Size = cnf.Size
+		C.XResizeWindow(w.x, w.xw, C.uint(cnf.Size.X), C.uint(cnf.Size.Y))
 	}
 
-	var title string
-	if o := cnf.Title; o != nil {
-		title = *o
+	if prev.Title != cnf.Title {
+		title := cnf.Title
+		ctitle := C.CString(title)
+		defer C.free(unsafe.Pointer(ctitle))
+		C.XStoreName(w.x, w.xw, ctitle)
+		// set _NET_WM_NAME as well for UTF-8 support in window title.
+		C.XSetTextProperty(w.x, w.xw,
+			&C.XTextProperty{
+				value:    (*C.uchar)(unsafe.Pointer(ctitle)),
+				encoding: w.atoms.utf8string,
+				format:   8,
+				nitems:   C.ulong(len(title)),
+			},
+			w.atoms.wmName)
 	}
-	ctitle := C.CString(title)
-	defer C.free(unsafe.Pointer(ctitle))
-	C.XStoreName(w.x, w.xw, ctitle)
-	// set _NET_WM_NAME as well for UTF-8 support in window title.
-	C.XSetTextProperty(w.x, w.xw,
-		&C.XTextProperty{
-			value:    (*C.uchar)(unsafe.Pointer(ctitle)),
-			encoding: w.atoms.utf8string,
-			format:   8,
-			nitems:   C.ulong(len(title)),
-		},
-		w.atoms.wmName)
 
-	if o := cnf.WindowMode; o != nil {
-		w.SetWindowMode(*o)
+	if prev.Mode != cnf.Mode {
+		w.SetWindowMode(cnf.Mode)
 	}
 }
 
+func (w *x11Window) Config() Config {
+	return w.config
+}
+
 func (w *x11Window) SetCursor(name pointer.CursorName) {
 	switch name {
 	case pointer.CursorNone:
@@ -182,13 +189,11 @@ func (w *x11Window) SetCursor(name pointer.CursorName) {
 	C.XDefineCursor(w.x, w.xw, c)
 }
 
-func (w *x11Window) SetWindowMode(mode windowMode) {
+func (w *x11Window) SetWindowMode(mode WindowMode) {
 	switch mode {
-	case w.mode:
-		return
-	case windowed:
+	case Windowed:
 		C.XDeleteProperty(w.x, w.xw, w.atoms.wmStateFullscreen)
-	case fullscreen:
+	case Fullscreen:
 		C.XChangeProperty(w.x, w.xw, w.atoms.wmState, C.XA_ATOM,
 			32, C.PropModeReplace,
 			(*C.uchar)(unsafe.Pointer(&w.atoms.wmStateFullscreen)), 1,
@@ -196,7 +201,7 @@ func (w *x11Window) SetWindowMode(mode windowMode) {
 	default:
 		return
 	}
-	w.mode = mode
+	w.config.Mode = mode
 	// "A Client wishing to change the state of a window MUST send
 	//  a _NET_WM_STATE client message to the root window (see below)."
 	var xev C.XEvent
@@ -261,7 +266,7 @@ func (w *x11Window) display() *C.Display {
 }
 
 func (w *x11Window) window() (C.Window, int, int) {
-	return w.xw, w.width, w.height
+	return w.xw, w.config.Size.X, w.config.Size.Y
 }
 
 func (w *x11Window) setStage(s system.Stage) {
@@ -327,15 +332,15 @@ loop:
 		default:
 		}
 
-		if (anim || syn) && w.width != 0 && w.height != 0 {
+		if (anim || syn) && w.config.Size.X != 0 && w.config.Size.Y != 0 {
 			w.w.Event(frameEvent{
 				FrameEvent: system.FrameEvent{
 					Now: time.Now(),
 					Size: image.Point{
-						X: w.width,
-						Y: w.height,
+						X: w.config.Size.X,
+						Y: w.config.Size.Y,
 					},
-					Metric: w.cfg,
+					Metric: w.metric,
 				},
 				Sync: syn,
 			})
@@ -491,8 +496,7 @@ func (h *x11EventHandler) handleEvents() bool {
 			w.w.Event(key.FocusEvent{Focus: false})
 		case C.ConfigureNotify: // window configuration change
 			cevt := (*C.XConfigureEvent)(unsafe.Pointer(xev))
-			w.width = int(cevt.width)
-			w.height = int(cevt.height)
+			w.config.Size = image.Pt(int(cevt.width), int(cevt.height))
 			// redraw will be done by a later expose event
 		case C.SelectionNotify:
 			cevt := (*C.XSelectionEvent)(unsafe.Pointer(xev))
@@ -583,7 +587,7 @@ func init() {
 	x11Driver = newX11Window
 }
 
-func newX11Window(gioWin *callbacks, cnf *config) error {
+func newX11Window(gioWin *callbacks, options []Option) error {
 	var err error
 
 	pipe := make([]int, 2)
@@ -623,6 +627,9 @@ func newX11Window(gioWin *callbacks, cnf *config) error {
 
 	ppsp := x11DetectUIScale(dpy)
 	cfg := unit.Metric{PxPerDp: ppsp, PxPerSp: ppsp}
+	var cnf Config
+	cnf.apply(cfg, options)
+
 	swa := C.XSetWindowAttributes{
 		event_mask: C.ExposureMask | C.FocusChangeMask | // update
 			C.KeyPressMask | C.KeyReleaseMask | // keyboard
@@ -632,24 +639,18 @@ func newX11Window(gioWin *callbacks, cnf *config) error {
 		background_pixmap: C.None,
 		override_redirect: C.False,
 	}
-	var width, height int
-	if o := cnf.Size; o != nil {
-		width = cfg.Px(o.Width)
-		height = cfg.Px(o.Height)
-	}
 	win := C.XCreateWindow(dpy, C.XDefaultRootWindow(dpy),
-		0, 0, C.uint(width), C.uint(height),
+		0, 0, C.uint(cnf.Size.X), C.uint(cnf.Size.Y),
 		0, C.CopyFromParent, C.InputOutput, nil,
 		C.CWEventMask|C.CWBackPixmap|C.CWOverrideRedirect, &swa)
 
 	w := &x11Window{
 		w: gioWin, x: dpy, xw: win,
-		width:        width,
-		height:       height,
-		cfg:          cfg,
+		metric:       cfg,
 		xkb:          xkb,
 		xkbEventBase: xkbEventBase,
 		wakeups:      make(chan struct{}, 1),
+		config:       cnf,
 	}
 	w.notify.read = pipe[0]
 	w.notify.write = pipe[1]
@@ -684,7 +685,7 @@ func newX11Window(gioWin *callbacks, cnf *config) error {
 	// extensions
 	C.XSetWMProtocols(dpy, win, &w.atoms.evDelWindow, 1)
 
-	w.Configure(cnf)
+	w.Configure(options)
 
 	// make the window visible on the screen
 	C.XMapWindow(dpy, win)
diff --git a/app/window.go b/app/window.go
index 08b05edb..9405e4a5 100644
--- a/app/window.go
+++ b/app/window.go
@@ -23,7 +23,7 @@ import (
 )
 
 // Option configures a window.
-type Option func(cnf *config)
+type Option func(unit.Metric, *Config)
 
 // Window represents an operating system window.
 type Window struct {
@@ -93,14 +93,13 @@ var ackEvent event.Event
 // Calling NewWindow more than once is not supported on
 // iOS, Android, WebAssembly.
 func NewWindow(options ...Option) *Window {
-	cnf := new(config)
-	// Default options.
-	Size(unit.Dp(800), unit.Dp(600))(cnf)
-	Title("Gio")(cnf)
-
-	for _, o := range options {
-		o(cnf)
+	defaultOptions := []Option{
+		Size(unit.Dp(800), unit.Dp(600)),
+		Title("Gio"),
 	}
+	options = append(defaultOptions, options...)
+	var cnf Config
+	cnf.apply(unit.Metric{}, options)
 
 	w := &Window{
 		in:           make(chan event.Event),
@@ -116,7 +115,7 @@ func NewWindow(options ...Option) *Window {
 		nocontext:    cnf.CustomRenderer,
 	}
 	w.callbacks.w = w
-	go w.run(cnf)
+	go w.run(options)
 	return w
 }
 
@@ -260,14 +259,21 @@ func (w *Window) Invalidate() {
 // Option applies the options to the window.
 func (w *Window) Option(opts ...Option) {
 	w.driverDefer(func(d driver) {
-		c := new(config)
-		for _, opt := range opts {
-			opt(c)
-		}
-		d.Configure(c)
+		d.Configure(opts)
 	})
 }
 
+// Config returns the Window configuration.
+//
+// A FrameEvent will occur whenever the configuration changes.
+func (w *Window) Config() Config {
+	var cnf Config
+	w.driverRun(func(d driver) {
+		cnf = d.Config()
+	})
+	return cnf
+}
+
 // ReadClipboard initiates a read of the clipboard in the form
 // of a clipboard.Event. Multiple reads may be coalesced
 // to a single event.
@@ -491,7 +497,7 @@ func (w *Window) waitFrame() (*op.Ops, bool) {
 	}
 }
 
-func (w *Window) run(cnf *config) {
+func (w *Window) run(options []Option) {
 	// Some OpenGL drivers don't like being made current on many different
 	// OS threads. Force the Go runtime to map the event loop goroutine to
 	// only one thread.
@@ -499,7 +505,7 @@ func (w *Window) run(cnf *config) {
 
 	defer close(w.out)
 	defer close(w.dead)
-	if err := newWindow(&w.callbacks, cnf); err != nil {
+	if err := newWindow(&w.callbacks, options); err != nil {
 		w.out <- system.DestroyEvent{Err: err}
 		return
 	}
@@ -602,44 +608,10 @@ func (q *queue) Events(k event.Tag) []event.Event {
 	return q.q.Events(k)
 }
 
-var (
-	// Windowed is the normal window mode with OS specific window decorations.
-	Windowed Option = modeOption(windowed)
-	// Fullscreen is the full screen window mode.
-	Fullscreen Option = modeOption(fullscreen)
-)
-
-// WindowMode sets the window mode.
-//
-// Supported platforms are macOS, X11, Windows and JS.
-func modeOption(mode windowMode) Option {
-	return func(cnf *config) {
-		cnf.WindowMode = &mode
-	}
-}
-
-var (
-	// AnyOrientation allows the window to be freely orientated.
-	AnyOrientation Option = orientationOption(anyOrientation)
-	// LandscapeOrientation constrains the window to landscape orientations.
-	LandscapeOrientation Option = orientationOption(landscapeOrientation)
-	// PortraitOrientation constrains the window to portrait orientations.
-	PortraitOrientation Option = orientationOption(portraitOrientation)
-)
-
-// orientation sets the orientation of the app.
-//
-// Supported platforms are Android and JS.
-func orientationOption(mode orientation) Option {
-	return func(cnf *config) {
-		cnf.Orientation = &mode
-	}
-}
-
 // Title sets the title of the window.
 func Title(t string) Option {
-	return func(cnf *config) {
-		cnf.Title = &t
+	return func(_ unit.Metric, cnf *Config) {
+		cnf.Title = t
 	}
 }
 
@@ -651,10 +623,10 @@ func Size(w, h unit.Value) Option {
 	if h.V <= 0 {
 		panic("height must be larger than or equal to 0")
 	}
-	return func(cnf *config) {
-		cnf.Size = &size{
-			Width:  w,
-			Height: h,
+	return func(m unit.Metric, cnf *Config) {
+		cnf.Size = image.Point{
+			X: m.Px(w),
+			Y: m.Px(h),
 		}
 	}
 }
@@ -667,10 +639,10 @@ func MaxSize(w, h unit.Value) Option {
 	if h.V <= 0 {
 		panic("height must be larger than or equal to 0")
 	}
-	return func(cnf *config) {
-		cnf.MaxSize = &size{
-			Width:  w,
-			Height: h,
+	return func(m unit.Metric, cnf *Config) {
+		cnf.MaxSize = image.Point{
+			X: m.Px(w),
+			Y: m.Px(h),
 		}
 	}
 }
@@ -683,32 +655,32 @@ func MinSize(w, h unit.Value) Option {
 	if h.V <= 0 {
 		panic("height must be larger than or equal to 0")
 	}
-	return func(cnf *config) {
-		cnf.MinSize = &size{
-			Width:  w,
-			Height: h,
+	return func(m unit.Metric, cnf *Config) {
+		cnf.MinSize = image.Point{
+			X: m.Px(w),
+			Y: m.Px(h),
 		}
 	}
 }
 
 // StatusColor sets the color of the Android status bar.
 func StatusColor(color color.NRGBA) Option {
-	return func(cnf *config) {
-		cnf.StatusColor = &color
+	return func(_ unit.Metric, cnf *Config) {
+		cnf.StatusColor = color
 	}
 }
 
 // NavigationColor sets the color of the navigation bar on Android, or the address bar in browsers.
 func NavigationColor(color color.NRGBA) Option {
-	return func(cnf *config) {
-		cnf.NavigationColor = &color
+	return func(_ unit.Metric, cnf *Config) {
+		cnf.NavigationColor = color
 	}
 }
 
-// CustomRenderer controls whether the the window contents is
+// CustomRenderer controls whether the window contents is
 // rendered by the client. If true, no GPU context is created.
 func CustomRenderer(custom bool) Option {
-	return func(cnf *config) {
+	return func(_ unit.Metric, cnf *Config) {
 		cnf.CustomRenderer = custom
 	}
 }