diff --git a/internal/uidriver/glfw/input.go b/internal/uidriver/glfw/input.go
index d1833be7c..f3ecd7269 100644
--- a/internal/uidriver/glfw/input.go
+++ b/internal/uidriver/glfw/input.go
@@ -47,6 +47,8 @@ type Input struct {
 	touches            map[int]pos // This is not updated until GLFW 3.3 is available (#417)
 	runeBuffer         []rune
 	ui                 *UserInterface
+
+	m sync.RWMutex
 }
 
 type pos struct {
@@ -55,15 +57,15 @@ type pos struct {
 }
 
 func (i *Input) CursorPosition() (x, y int) {
-	i.ui.m.RLock()
+	i.m.RLock()
 	cx, cy := i.cursorX, i.cursorY
-	i.ui.m.RUnlock()
+	i.m.RUnlock()
 	return i.ui.adjustPosition(cx, cy)
 }
 
 func (i *Input) GamepadIDs() []int {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	if len(i.gamepads) == 0 {
 		return nil
 	}
@@ -77,8 +79,8 @@ func (i *Input) GamepadIDs() []int {
 }
 
 func (i *Input) GamepadAxisNum(id int) int {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	if len(i.gamepads) <= id {
 		return 0
 	}
@@ -86,8 +88,8 @@ func (i *Input) GamepadAxisNum(id int) int {
 }
 
 func (i *Input) GamepadAxis(id int, axis int) float64 {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	if len(i.gamepads) <= id {
 		return 0
 	}
@@ -95,8 +97,8 @@ func (i *Input) GamepadAxis(id int, axis int) float64 {
 }
 
 func (i *Input) GamepadButtonNum(id int) int {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	if len(i.gamepads) <= id {
 		return 0
 	}
@@ -104,8 +106,8 @@ func (i *Input) GamepadButtonNum(id int) int {
 }
 
 func (i *Input) IsGamepadButtonPressed(id int, button driver.GamepadButton) bool {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	if len(i.gamepads) <= id {
 		return false
 	}
@@ -113,8 +115,8 @@ func (i *Input) IsGamepadButtonPressed(id int, button driver.GamepadButton) bool
 }
 
 func (i *Input) TouchIDs() []int {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 
 	if len(i.touches) == 0 {
 		return nil
@@ -128,7 +130,7 @@ func (i *Input) TouchIDs() []int {
 }
 
 func (i *Input) TouchPosition(id int) (x, y int) {
-	i.ui.m.RLock()
+	i.m.RLock()
 	found := false
 	var p pos
 	for tid, pos := range i.touches {
@@ -138,7 +140,7 @@ func (i *Input) TouchPosition(id int) (x, y int) {
 			break
 		}
 	}
-	i.ui.m.RUnlock()
+	i.m.RUnlock()
 
 	if !found {
 		return 0, 0
@@ -147,21 +149,21 @@ func (i *Input) TouchPosition(id int) (x, y int) {
 }
 
 func (i *Input) RuneBuffer() []rune {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	return i.runeBuffer
 }
 
 func (i *Input) ResetForFrame() {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	i.runeBuffer = i.runeBuffer[:0]
 	i.scrollX, i.scrollY = 0, 0
 }
 
 func (i *Input) IsKeyPressed(key driver.Key) bool {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	if i.keyPressed == nil {
 		i.keyPressed = map[glfw.Key]bool{}
 	}
@@ -177,8 +179,8 @@ func (i *Input) IsKeyPressed(key driver.Key) bool {
 }
 
 func (i *Input) IsMouseButtonPressed(button driver.MouseButton) bool {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	if i.mouseButtonPressed == nil {
 		i.mouseButtonPressed = map[glfw.MouseButton]bool{}
 	}
@@ -194,8 +196,8 @@ func (i *Input) IsMouseButtonPressed(button driver.MouseButton) bool {
 }
 
 func (i *Input) Wheel() (xoff, yoff float64) {
-	i.ui.m.RLock()
-	defer i.ui.m.RUnlock()
+	i.m.RLock()
+	defer i.m.RUnlock()
 	return i.scrollX, i.scrollY
 }
 
@@ -209,21 +211,21 @@ func (i *Input) appendRuneBuffer(char rune) {
 	if !unicode.IsPrint(char) {
 		return
 	}
-	i.ui.m.Lock()
+	i.m.Lock()
 	i.runeBuffer = append(i.runeBuffer, char)
-	i.ui.m.Unlock()
+	i.m.Unlock()
 }
 
 func (i *Input) setWheel(xoff, yoff float64) {
-	i.ui.m.Lock()
+	i.m.Lock()
 	i.scrollX = xoff
 	i.scrollY = yoff
-	i.ui.m.Unlock()
+	i.m.Unlock()
 }
 
-func (i *Input) update(window *glfw.Window, scale float64) {
-	i.ui.m.Lock()
-	defer i.ui.m.Unlock()
+func (i *Input) update(window *glfw.Window) {
+	i.m.Lock()
+	defer i.m.Unlock()
 
 	i.onceCallback.Do(func() {
 		window.SetCharModsCallback(func(w *glfw.Window, char rune, mods glfw.ModifierKey) {
@@ -246,8 +248,8 @@ func (i *Input) update(window *glfw.Window, scale float64) {
 		i.mouseButtonPressed[gb] = window.GetMouseButton(gb) == glfw.Press
 	}
 	x, y := window.GetCursorPos()
-	i.cursorX = int(x / scale)
-	i.cursorY = int(y / scale)
+	i.cursorX = int(i.ui.toDeviceIndependentPixel(x) / i.ui.getScale())
+	i.cursorY = int(i.ui.toDeviceIndependentPixel(y) / i.ui.getScale())
 	for id := glfw.Joystick(0); id < glfw.Joystick(len(i.gamepads)); id++ {
 		i.gamepads[id].valid = false
 		if !id.Present() {
diff --git a/internal/uidriver/glfw/ui.go b/internal/uidriver/glfw/ui.go
index 200f45692..169d73362 100644
--- a/internal/uidriver/glfw/ui.go
+++ b/internal/uidriver/glfw/ui.go
@@ -134,9 +134,8 @@ func initialize() error {
 	theUI.window = w
 	theUI.initMonitor = theUI.currentMonitorFromPosition()
 	v := theUI.initMonitor.GetVideoMode()
-	s := theUI.glfwScale()
-	theUI.initFullscreenWidth = int(float64(v.Width) / s)
-	theUI.initFullscreenHeight = int(float64(v.Height) / s)
+	theUI.initFullscreenWidth = int(theUI.toDeviceIndependentPixel(float64(v.Width)))
+	theUI.initFullscreenHeight = int(theUI.toDeviceIndependentPixel(float64(v.Height)))
 	theUI.window.Destroy()
 	theUI.window = nil
 
@@ -306,19 +305,29 @@ func (u *UserInterface) setInitWindowPosition(x, y int) {
 	u.initWindowPositionY = y
 }
 
+// toDeviceIndependentPixel must be called from the main thread.
+func (u *UserInterface) toDeviceIndependentPixel(x float64) float64 {
+	return x / u.glfwScale()
+}
+
+// toDeviceDependentPixel must be called from the main thread.
+func (u *UserInterface) toDeviceDependentPixel(x float64) float64 {
+	return x * u.glfwScale()
+}
+
 func (u *UserInterface) ScreenSizeInFullscreen() (int, int) {
 	if !u.isRunning() {
 		return u.initFullscreenWidth, u.initFullscreenHeight
 	}
 
-	var v *glfw.VidMode
-	s := 0.0
+	var w, h int
 	_ = u.t.Call(func() error {
-		v = u.currentMonitor().GetVideoMode()
-		s = u.glfwScale()
+		v := u.currentMonitor().GetVideoMode()
+		w = int(u.toDeviceIndependentPixel(float64(v.Width)))
+		h = int(u.toDeviceIndependentPixel(float64(v.Height)))
 		return nil
 	})
-	return int(float64(v.Width) / s), int(float64(v.Height) / s)
+	return w, h
 }
 
 func (u *UserInterface) SetScreenSize(width, height int) {
@@ -446,21 +455,18 @@ func (u *UserInterface) ScreenPadding() (x0, y0, x1, y1 float64) {
 	d := 0.0
 	sx := 0.0
 	sy := 0.0
-	gs := 0.0
-	vw := 0.0
-	vh := 0.0
+	mx := 0.0
+	my := 0.0
 	_ = u.t.Call(func() error {
-		d = u.deviceScaleFactor()
 		sx = float64(u.width) * u.actualScreenScale()
 		sy = float64(u.height) * u.actualScreenScale()
-		gs = u.glfwScale()
 
-		v := u.window.GetMonitor().GetVideoMode()
-		vw, vh = float64(v.Width), float64(v.Height)
+		v := u.currentMonitor().GetVideoMode()
+		d = u.deviceScaleFactor()
+		mx = u.toDeviceIndependentPixel(float64(v.Width)) * d
+		my = u.toDeviceIndependentPixel(float64(v.Height)) * d
 		return nil
 	})
-	mx := vw * d / gs
-	my := vh * d / gs
 
 	ox := (mx - sx) / 2
 	oy := (my - sy) / 2
@@ -659,9 +665,8 @@ func (u *UserInterface) createWindow() error {
 			return
 		}
 
-		s := u.glfwScale()
-		w := int(float64(width) / u.scale / s)
-		h := int(float64(height) / u.scale / s)
+		w := int(u.toDeviceIndependentPixel(float64(width)) / u.scale)
+		h := int(u.toDeviceIndependentPixel(float64(height)) / u.scale)
 		u.reqWidth = w
 		u.reqHeight = h
 	})
@@ -745,8 +750,8 @@ func (u *UserInterface) run(width, height int, scale float64, title string, cont
 
 	_ = u.t.Call(func() error {
 		// Get the window size before showing since window.Show might change the current
-		// monitor which affects glfwSize result.
-		w, h := u.glfwSize()
+		// monitor which affects deviceDependentWindowSize result.
+		w, h := u.deviceDependentWindowSize()
 
 		u.title = title
 		u.window.SetTitle(title)
@@ -774,10 +779,10 @@ func (u *UserInterface) run(width, height int, scale float64, title string, cont
 	return u.loop(context)
 }
 
-// getSize must be called from the main thread.
-func (u *UserInterface) glfwSize() (int, int) {
-	w := int(float64(u.windowWidth) * u.getScale() * u.glfwScale())
-	h := int(float64(u.height) * u.getScale() * u.glfwScale())
+// deviceDependentWindowSize must be called from the main thread.
+func (u *UserInterface) deviceDependentWindowSize() (int, int) {
+	w := int(u.toDeviceDependentPixel(float64(u.windowWidth) * u.getScale()))
+	h := int(u.toDeviceDependentPixel(float64(u.height) * u.getScale()))
 	return w, h
 }
 
@@ -787,9 +792,9 @@ func (u *UserInterface) getScale() float64 {
 		return u.scale
 	}
 	if u.fullscreenScale == 0 {
-		v := u.window.GetMonitor().GetVideoMode()
-		sw := float64(v.Width) / u.glfwScale() / float64(u.width)
-		sh := float64(v.Height) / u.glfwScale() / float64(u.height)
+		v := u.currentMonitor().GetVideoMode()
+		sw := u.toDeviceIndependentPixel(float64(v.Width)) / float64(u.width)
+		sh := u.toDeviceIndependentPixel(float64(v.Height)) / float64(u.height)
 		s := sw
 		if s > sh {
 			s = sh
@@ -848,7 +853,7 @@ func (u *UserInterface) update(context driver.UIContext) error {
 	_ = u.t.Call(func() error {
 		glfw.PollEvents()
 
-		u.input.update(u.window, u.getScale()*u.glfwScale())
+		u.input.update(u.window)
 
 		defer hooks.ResumeAudio()
 
@@ -1018,14 +1023,14 @@ func (u *UserInterface) setScreenSize(width, height int, scale float64, fullscre
 			}
 
 			oldW, oldH := u.window.GetSize()
-			newW, newH := u.glfwSize()
+			newW, newH := u.deviceDependentWindowSize()
 			if oldW != newW || oldH != newH {
 				ch := make(chan struct{})
 				u.window.SetFramebufferSizeCallback(func(_ *glfw.Window, _, _ int) {
 					u.window.SetFramebufferSizeCallback(nil)
 					close(ch)
 				})
-				u.window.SetSize(u.glfwSize())
+				u.window.SetSize(newW, newH)
 			event:
 				for {
 					glfw.PollEvents()