Add clipboard to fyne.App. Fixes fyne-io#4418.

NB. getting a lot of errors when running go test ./..., unrelated
to this change. Will investigate some of them as they relate to the
locale, others I have no idea.

app.go

@@ -79,6 +79,11 @@ type App interface {
 	//
 	// Since: 2.3
 	SetCloudProvider(CloudProvider) // configure cloud for this app
+
+	// Clipboard returns the system clipboard.
+	//
+	// Since: 2.6
+	Clipboard() Clipboard
 }
 
 var app atomic.Pointer[App]

app/app.go

@@ -109,6 +109,10 @@ func (a *fyneApp) newDefaultPreferences() *preferences {
 	return p
 }
 
+func (a *fyneApp) Clipboard() fyne.Clipboard {
+	return a.Driver().Clipboard()
+}
+
 // New returns a new application instance with the default driver and no unique ID (unless specified in FyneApp.toml)
 func New() fyne.App {
 	if meta.ID == "" {

app_test.go

@@ -68,6 +68,10 @@ func (dummyApp) Metadata() AppMetadata {
 	return AppMetadata{}
 }
 
+func (dummyApp) Clipboard() Clipboard {
+	return nil
+}
+
 func TestSetCurrentApp(t *testing.T) {
 	a := &dummyApp{}
 	SetCurrentApp(a)

cmd/fyne_demo/main.go

@@ -133,19 +133,19 @@ func makeMenu(a fyne.App, w fyne.Window) *fyne.MainMenu {
 		openSettings()
 	})
 
-	cutShortcut := &fyne.ShortcutCut{Clipboard: w.Clipboard()}
+	cutShortcut := &fyne.ShortcutCut{Clipboard: a.Clipboard()}
 	cutItem := fyne.NewMenuItem("Cut", func() {
-		shortcutFocused(cutShortcut, w)
+		shortcutFocused(cutShortcut, a, w)
 	})
 	cutItem.Shortcut = cutShortcut
-	copyShortcut := &fyne.ShortcutCopy{Clipboard: w.Clipboard()}
+	copyShortcut := &fyne.ShortcutCopy{Clipboard: a.Clipboard()}
 	copyItem := fyne.NewMenuItem("Copy", func() {
-		shortcutFocused(copyShortcut, w)
+		shortcutFocused(copyShortcut, a, w)
 	})
 	copyItem.Shortcut = copyShortcut
-	pasteShortcut := &fyne.ShortcutPaste{Clipboard: w.Clipboard()}
+	pasteShortcut := &fyne.ShortcutPaste{Clipboard: a.Clipboard()}
 	pasteItem := fyne.NewMenuItem("Paste", func() {
-		shortcutFocused(pasteShortcut, w)
+		shortcutFocused(pasteShortcut, a, w)
 	})
 	pasteItem.Shortcut = pasteShortcut
 	performFind := func() { fmt.Println("Menu Find") }
@@ -251,14 +251,14 @@ func makeNav(setTutorial func(tutorial tutorials.Tutorial), loadPrevious bool) f
 	return container.NewBorder(nil, themes, nil, nil, tree)
 }
 
-func shortcutFocused(s fyne.Shortcut, w fyne.Window) {
+func shortcutFocused(s fyne.Shortcut, a fyne.App, w fyne.Window) {
 	switch sh := s.(type) {
 	case *fyne.ShortcutCopy:
-		sh.Clipboard = w.Clipboard()
+		sh.Clipboard = a.Clipboard()
 	case *fyne.ShortcutCut:
-		sh.Clipboard = w.Clipboard()
+		sh.Clipboard = a.Clipboard()
 	case *fyne.ShortcutPaste:
-		sh.Clipboard = w.Clipboard()
+		sh.Clipboard = a.Clipboard()
 	}
 	if focused, ok := w.Canvas().Focused().(fyne.Shortcutable); ok {
 		focused.TypedShortcut(s)

driver.go

@@ -43,4 +43,9 @@ type Driver interface {
 	//
 	// Since: 2.5
 	SetDisableScreenBlanking(bool)
+
+	// Clipboard returns the system clipboard.
+	//
+	// Since: 2.6
+	Clipboard() Clipboard
 }

internal/driver/glfw/driver.go

@@ -68,6 +68,10 @@ func toOSIcon(icon []byte) ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
+func (d *gLDriver) Clipboard() fyne.Clipboard {
+	return &clipboard{}
+}
+
 func (d *gLDriver) RenderedTextSize(text string, textSize float32, style fyne.TextStyle, source fyne.Resource) (size fyne.Size, baseline float32) {
 	return painter.RenderedTextSize(text, textSize, style, source)
 }

internal/driver/mobile/driver.go

@@ -100,6 +100,10 @@ func (d *driver) currentWindow() *window {
 	return last
 }
 
+func (d *driver) Clipboard() fyne.Clipboard {
+	return &mobileClipboard{}
+}
+
 func (d *driver) RenderedTextSize(text string, textSize float32, style fyne.TextStyle, source fyne.Resource) (size fyne.Size, baseline float32) {
 	return painter.RenderedTextSize(text, textSize, style, source)
 }

test/app.go

@@ -63,6 +63,10 @@ func (a *app) Quit() {
 	// no-op
 }
 
+func (a *app) Clipboard() fyne.Clipboard {
+	return nil
+}
+
 func (a *app) UniqueID() string {
 	return "testApp" // TODO should this be randomised?
 }

test/driver.go

@@ -116,6 +116,10 @@ func (d *driver) Quit() {
 	// no-op
 }
 
+func (d *driver) Clipboard() fyne.Clipboard {
+	return nil
+}
+
 func (d *driver) removeWindow(w *window) {
 	d.windowsMutex.Lock()
 	i := 0

theme/themedtestapp_test.go

@@ -106,3 +106,7 @@ func (t *themedApp) ShowAnimations() bool {
 
 func (t *themedApp) AddChangeListener(chan fyne.Settings) {
 }
+
+func (t *themedApp) Clipboard() fyne.Clipboard {
+	return nil
+}

window.go

@@ -101,5 +101,7 @@ type Window interface {
 	Canvas() Canvas
 
 	// Clipboard returns the system clipboard
+	//
+	// Deprecated: use App.Clipboard() instead.
 	Clipboard() Clipboard
 }