add custom MouseBack/Forward APIs

canvas.go

@@ -44,6 +44,10 @@ type Canvas interface {
 	AddShortcut(shortcut Shortcut, handler func(shortcut Shortcut))
 	RemoveShortcut(shortcut Shortcut)
 
+	// Supersonic-specific extensions
+	SetOnMouseBack(func())
+	SetOnMouseForward(func())
+
 	Capture() image.Image
 
 	// PixelCoordinateForPosition returns the x and y pixel coordinate for a given position on this canvas.

driver/desktop/mouse.go

@@ -23,6 +23,16 @@ const (
 	// Since: 2.0
 	MouseButtonTertiary
 
+	// MouseButtonBack is the back mouse button
+	//
+	// Since: <Supersonic specific extension>
+	MouseButtonBack
+
+	// MouseButtonForward is the back mouse button
+	//
+	// Since: <Supersonic specific extension>
+	MouseButtonForward
+
 	// LeftMouseButton is the most common mouse button - on some systems the only one.
 	//
 	// Deprecated: use MouseButtonPrimary which will adapt to mouse configuration.

internal/driver/glfw/canvas.go

@@ -25,10 +25,12 @@ type glCanvas struct {
 	padded, debug bool
 	size          fyne.Size
 
-	onTypedRune func(rune)
-	onTypedKey  func(*fyne.KeyEvent)
-	onKeyDown   func(*fyne.KeyEvent)
-	onKeyUp     func(*fyne.KeyEvent)
+	onTypedRune    func(rune)
+	onTypedKey     func(*fyne.KeyEvent)
+	onKeyDown      func(*fyne.KeyEvent)
+	onKeyUp        func(*fyne.KeyEvent)
+	onMouseBack    func()
+	onMouseForward func()
 	// shortcut    fyne.ShortcutHandler
 
 	scale, detectedScale, texScale float32
@@ -178,6 +180,14 @@ func (c *glCanvas) SetOnTypedRune(typed func(rune)) {
 	c.onTypedRune = typed
 }
 
+func (c *glCanvas) SetOnMouseBack(fn func()) {
+	c.onMouseBack = fn
+}
+
+func (c *glCanvas) SetOnMouseForward(fn func()) {
+	c.onMouseForward = fn
+}
+
 func (c *glCanvas) SetPadded(padded bool) {
 	c.Lock()
 	content := c.content

internal/driver/glfw/window.go

@@ -513,6 +513,15 @@ func (w *window) processMouseClicked(button desktop.MouseButton, action action,
 		w.mouseLock.Unlock()
 	}
 
+	if button == desktop.MouseButtonBack || button == desktop.MouseButtonForward {
+		if w.canvas.onMouseBack != nil && button == desktop.MouseButtonBack {
+			w.canvas.onMouseBack()
+		} else if w.canvas.onMouseForward != nil && button == desktop.MouseButtonForward {
+			w.canvas.onMouseForward()
+		}
+		return
+	}
+
 	co, pos, _ := w.findObjectAtPositionMatching(w.canvas, mousePos, func(object fyne.CanvasObject) bool {
 		switch object.(type) {
 		case fyne.Tappable, fyne.SecondaryTappable, fyne.DoubleTappable, fyne.Focusable, desktop.Mouseable, desktop.Hoverable:

internal/driver/glfw/window_desktop.go

@@ -421,6 +421,10 @@ func convertMouseButton(btn glfw.MouseButton, mods glfw.ModifierKey) (desktop.Mo
 		button = desktop.MouseButtonSecondary
 	case glfw.MouseButton3:
 		button = desktop.MouseButtonTertiary
+	case glfw.MouseButton4:
+		button = desktop.MouseButtonBack
+	case glfw.MouseButton5:
+		button = desktop.MouseButtonForward
 	}
 	return button, modifier
 }

internal/driver/mobile/canvas.go

@@ -112,6 +112,10 @@ func (c *mobileCanvas) SetOnTypedRune(typed func(rune)) {
 	c.onTypedRune = typed
 }
 
+func (*mobileCanvas) SetOnMouseBack(func()) {}
+
+func (*mobileCanvas) SetOnMouseForward(func()) {}
+
 func (c *mobileCanvas) Size() fyne.Size {
 	return c.size
 }