fix: synchronize close state in glfw window (#3874)

internal/driver/glfw/loop.go

@@ -193,7 +193,7 @@ func (d *gLDriver) runGL() {
 
 func (d *gLDriver) destroyWindow(w *window, index int) {
 	w.visible = false
-	w.viewport.Destroy()
+	w.destroyViewport()
 	w.destroy(d)
 
 	if index < len(d.windows)-1 {

internal/driver/glfw/window.go

@@ -896,10 +896,11 @@ func (w *window) triggerMainMenuShortcut(sh fyne.Shortcut) bool {
 }
 
 func (w *window) RunWithContext(f func()) {
-	if w.isClosing() {
+	v := w.view()
+	if v == nil {
 		return
 	}
-	w.view().MakeContextCurrent()
+	v.MakeContextCurrent()
 
 	f()
 

internal/driver/glfw/window_desktop.go

@@ -892,6 +892,19 @@ func (w *window) view() *glfw.Window {
 	return w.viewport
 }
 
+// destroyViewport destroys the underlying GLFW window and clears the pointer
+// first, so a later view() / isClosing() observes the destruction and never
+// hands out a pointer to an already-destroyed window. Safe to call once; later
+// calls are no-ops. Must run on the main goroutine, like the rest of the GLFW
+// lifecycle.
+func (w *window) destroyViewport() {
+	vp := w.viewport
+	w.viewport = nil
+	if vp != nil {
+		vp.Destroy()
+	}
+}
+
 // wrapInnerWindow is a no-op to match what the web driver provides
 func wrapInnerWindow(*container.InnerWindow, fyne.Window, *gLDriver) fyne.Window {
 	return nil

internal/driver/glfw/window_test.go

@@ -1818,6 +1818,20 @@ func TestWindow_ClosedBeforeShow(t *testing.T) {
 	assert.NotPanics(t, func() { w.closed(nil) })
 }
 
+// fyne#3874: viewport.Destroy() does not nil w.viewport, so view() keeps
+// handing a dead handle to the draw thread. After Destroy(), view() must
+// return nil — otherwise RunWithContext drives MakeContextCurrent on a
+// destroyed GLFW window (SIGSEGV on macOS, BadWindow on X11).
+func TestWindow_RunWithContext_AfterViewportDestroyed(t *testing.T) {
+	w := createWindow("Race-Destroyed")
+
+	runOnMain(func() {
+		w.window.destroyViewport()
+	})
+
+	require.Nil(t, w.window.view(), "view() must be nil after destroyViewport()")
+}
+
 func TestWindow_SetContent_Twice(t *testing.T) {
 	w := createWindow("Test")
 

internal/driver/glfw/window_wasm.go

@@ -592,6 +592,19 @@ func (w *window) view() *glfw.Window {
 	return w.viewport
 }
 
+// destroyViewport destroys the underlying GLFW window and clears the pointer
+// first, so a later view() / isClosing() observes the destruction and never
+// hands out a pointer to an already-destroyed window. Safe to call once; later
+// calls are no-ops. Must run on the main goroutine, like the rest of the GLFW
+// lifecycle.
+func (w *window) destroyViewport() {
+	vp := w.viewport
+	w.viewport = nil
+	if vp != nil {
+		vp.Destroy()
+	}
+}
+
 // wrapInner represents a window that is provided by an InnerWindow container in the canvas.
 type wrapInner struct {
 	fyne.Window