driver/glfw: Merge waitForStart and done channels

With the threading changes, we no longer need to have separate
channels for done and waitForStart given that showing a window no
longer is expected to happen on the wrong thread. This allows
allows us to first wait for starting and then reopen the channel
to wait for shutting down.

internal/driver/glfw/driver.go

@@ -33,10 +33,9 @@ var curWindow *window
 var _ fyne.Driver = (*gLDriver)(nil)
 
 type gLDriver struct {
-	windowLock   sync.RWMutex
-	windows      []fyne.Window
-	done         chan struct{}
-	waitForStart chan struct{}
+	windowLock        sync.RWMutex
+	windows           []fyne.Window
+	waitForTransition chan struct{} // wait for transitioning first from starting and later on to quiting.
 
 	animation animation.Runner
 
@@ -99,7 +98,7 @@ func (d *gLDriver) Quit() {
 
 	// Only call close once to avoid panic.
 	if running.CompareAndSwap(true, false) {
-		close(d.done)
+		close(d.waitForTransition)
 	}
 }
 
@@ -174,7 +173,6 @@ func NewGLDriver() *gLDriver {
 	repository.Register("file", intRepo.NewFileRepository())
 
 	return &gLDriver{
-		done:         make(chan struct{}),
-		waitForStart: make(chan struct{}),
+		waitForTransition: make(chan struct{}),
 	}
 }

internal/driver/glfw/glfw_test.go

@@ -32,10 +32,6 @@ func ensureCanvasSize(t *testing.T, w *window, size fyne.Size) {
 }
 
 func repaintWindow(w *window) {
-	// Wait for GLFW loop to be running.
-	// If we try to paint windows before the context is created, we will end up on the wrong thread.
-	<-w.driver.waitForStart
-
 	runOnMainWithContext(w, func() {
 		d.repaintWindow(w)
 	})

internal/driver/glfw/loop.go

@@ -93,7 +93,9 @@ func (d *gLDriver) runGL() {
 	if !running.CompareAndSwap(false, true) {
 		return // Run was called twice.
 	}
-	close(d.waitForStart) // Signal that execution can continue.
+
+	close(d.waitForTransition)                // Signal that execution can continue.
+	d.waitForTransition = make(chan struct{}) // Prepare for transitioning into done.
 
 	d.initGLFW()
 	if d.trayStart != nil {
@@ -109,7 +111,7 @@ func (d *gLDriver) runGL() {
 	eventTick := time.NewTicker(time.Second / 60)
 	for {
 		select {
-		case <-d.done:
+		case <-d.waitForTransition:
 			eventTick.Stop()
 			d.Terminate()
 			l := fyne.CurrentApp().Lifecycle().(*app.Lifecycle)

internal/driver/glfw/window.go

@@ -140,8 +140,6 @@ func (w *window) doShow() {
 		return
 	}
 
-	<-w.driver.waitForStart
-
 	w.createLock.Do(w.create)
 	if w.view() == nil {
 		return

internal/driver/glfw/window_test.go

@@ -38,9 +38,6 @@ func init() {
 func TestMain(m *testing.M) {
 	d.initGLFW()
 	go func() {
-		// Wait for GLFW loop to be running.
-		// If we try to create windows before the context is created, this will fail with an exception.
-		<-d.waitForStart
 
 		initMainMenu()
 		os.Exit(m.Run())