shiny: windriver: close client windows

After receiving a close request from the window manager,
DestroyWindow must be called to actually close the window.
This is done by DefWindowProc.

Fixes golang/go#25587

Change-Id: I05c95046ce4572fec0cba67eba2d313f318e36ba
Reviewed-on: https://go-review.googlesource.com/115515
Reviewed-by: Brad Fitzpatrick <[email protected]>

Author: elmar

shiny/driver/internal/win32/win32.go

@@ -170,8 +170,11 @@ func sendSize(hwnd syscall.Handle) {
 }
 
 func sendClose(hwnd syscall.Handle, uMsg uint32, wParam, lParam uintptr) (lResult uintptr) {
+	// TODO(ktye): DefWindowProc calls DestroyWindow by default.
+	// To intercept destruction of the window, return 0 and call
+	// DestroyWindow when appropriate.
 	LifecycleEvent(hwnd, lifecycle.StageDead)
-	return 0
+	return _DefWindowProc(hwnd, uMsg, wParam, lParam)
 }
 
 func sendMouseEvent(hwnd syscall.Handle, uMsg uint32, wParam, lParam uintptr) (lResult uintptr) {