Migrate preference in bindings after cloud changes

data/binding/gen.go

@@ -174,6 +174,10 @@ func (b *prefBound{{ .Name }}) checkForChange() {
 
 	b.trigger()
 }
+
+func (b *prefBound{{ .Name }}) replaceProvider(p fyne.Preferences) {
+	b.p = p
+}
 `
 
 const toStringTemplate = `

data/binding/pref_helper.go

@@ -42,6 +42,8 @@ func (b *preferenceBindings) setItem(key string, item preferenceItem) {
 type preferencesMap struct {
 	lock  sync.RWMutex
 	prefs map[fyne.Preferences]*preferenceBindings
+
+	appPrefs fyne.Preferences // the main application prefs, to check if it changed...
 }
 
 func newPreferencesMap() *preferencesMap {
@@ -74,6 +76,14 @@ func (m *preferencesMap) ensurePreferencesAttached(p fyne.Preferences) *preferen
 
 func (m *preferencesMap) getBindings(p fyne.Preferences) *preferenceBindings {
 	m.lock.RLock()
+	if p == fyne.CurrentApp().Preferences() {
+		if m.appPrefs == nil {
+			m.appPrefs = p
+		} else if m.appPrefs != p {
+			m.migratePreferences(m.appPrefs, p)
+		}
+	}
+
 	binds := m.prefs[p]
 	m.lock.RUnlock()
 	return binds
@@ -88,3 +98,17 @@ func (m *preferencesMap) preferencesChanged(p fyne.Preferences) {
 		item.checkForChange()
 	}
 }
+
+func (m *preferencesMap) migratePreferences(p1, p2 fyne.Preferences) {
+	m.prefs[p2] = m.prefs[p1]
+	delete(m.prefs, p1)
+	m.appPrefs = p2
+
+	for _, b := range m.prefs[p2].list() {
+		if backed, ok := b.(interface{ replaceProvider(fyne.Preferences) }); ok {
+			backed.replaceProvider(p2)
+		}
+	}
+
+	m.preferencesChanged(p2)
+}

data/binding/preference.go

@@ -69,6 +69,10 @@ func (b *prefBoundBool) checkForChange() {
 	b.trigger()
 }
 
+func (b *prefBoundBool) replaceProvider(p fyne.Preferences) {
+	b.p = p
+}
+
 type prefBoundFloat struct {
 	base
 	key string
@@ -127,6 +131,10 @@ func (b *prefBoundFloat) checkForChange() {
 	b.trigger()
 }
 
+func (b *prefBoundFloat) replaceProvider(p fyne.Preferences) {
+	b.p = p
+}
+
 type prefBoundInt struct {
 	base
 	key string
@@ -185,6 +193,10 @@ func (b *prefBoundInt) checkForChange() {
 	b.trigger()
 }
 
+func (b *prefBoundInt) replaceProvider(p fyne.Preferences) {
+	b.p = p
+}
+
 type prefBoundString struct {
 	base
 	key string
@@ -242,3 +254,7 @@ func (b *prefBoundString) checkForChange() {
 
 	b.trigger()
 }
+
+func (b *prefBoundString) replaceProvider(p fyne.Preferences) {
+	b.p = p
+}

data/binding/preference_test.go

@@ -135,6 +135,7 @@ func TestPreferenceBindingCopies(t *testing.T) {
 func TestPreferenceBindingTriggers(t *testing.T) {
 	a := test.NewApp()
 	p := a.Preferences()
+	prefBinds.appPrefs = nil // reset app migration checks
 	key := "test-string"
 
 	p.SetString(key, "aString")