address review comments

app/app_windows.go

@@ -90,5 +90,7 @@ func runScript(name, script string) {
 }
 
 func watchTheme(s *settings) {
-	go internalapp.WatchTheme(s.setupTheme)
+	go internalapp.WatchTheme(func() {
+		fyne.Do(s.setupTheme)
+	})
 }

app/settings.go

@@ -81,14 +81,12 @@ func (s *settings) ThemeVariant() fyne.ThemeVariant {
 	return s.variant
 }
 
-// must be called from main goroutine
 func (s *settings) applyTheme(theme fyne.Theme, variant fyne.ThemeVariant) {
 	s.variant = variant
 	s.theme = theme
 	s.apply()
 }
 
-// must be called from main goroutine
 func (s *settings) applyVariant(variant fyne.ThemeVariant) {
 	s.variant = variant
 	s.apply()
@@ -168,13 +166,7 @@ func (s *settings) setupTheme() {
 		variant = theme.VariantDark
 	}
 
-	if async.IsMainGoroutine() {
-		s.applyTheme(effectiveTheme, variant)
-	} else {
-		fyne.Do(func() {
-			s.applyTheme(effectiveTheme, variant)
-		})
-	}
+	s.applyTheme(effectiveTheme, variant)
 }
 
 func loadSettings() *settings {

internal/driver/glfw/loop.go

@@ -99,15 +99,24 @@ func (d *gLDriver) runGL() {
 	if d.trayStart != nil {
 		d.trayStart()
 	}
-	if f := fyne.CurrentApp().Lifecycle().(*app.Lifecycle).OnStarted(); f != nil {
-		f()
-	}
 
-	var pendingSettings fyne.Settings
 	fyne.CurrentApp().Settings().AddListener(func(set fyne.Settings) {
-		pendingSettings = set
+		painter.ClearFontCache()
+		cache.ResetThemeCaches()
+		app.ApplySettingsWithCallback(set, fyne.CurrentApp(), func(w fyne.Window) {
+			c, ok := w.Canvas().(*glCanvas)
+			if !ok {
+				return
+			}
+			c.applyThemeOutOfTreeObjects()
+			c.reloadScale()
+		})
 	})
 
+	if f := fyne.CurrentApp().Lifecycle().(*app.Lifecycle).OnStarted(); f != nil {
+		f()
+	}
+
 	eventTick := time.NewTicker(time.Second / 60)
 	for {
 		select {
@@ -156,20 +165,6 @@ func (d *gLDriver) runGL() {
 			d.animation.TickAnimations()
 			d.drawSingleFrame()
 		}
-
-		if pendingSettings != nil {
-			painter.ClearFontCache()
-			cache.ResetThemeCaches()
-			app.ApplySettingsWithCallback(pendingSettings, fyne.CurrentApp(), func(w fyne.Window) {
-				c, ok := w.Canvas().(*glCanvas)
-				if !ok {
-					return
-				}
-				c.applyThemeOutOfTreeObjects()
-				c.reloadScale()
-			})
-			pendingSettings = nil
-		}
 	}
 }