ui/app,apps/gophers,apps/hello: revert NewWindow to CreateWindow

It turns out we already support multiple windows on Android: when
the activity is recreated.

This reverts commit f21b5eb1df.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

apps/gophers/main.go

@@ -121,6 +121,14 @@ func main() {
 		fmt.Println("The quota for anonymous GitHub API access is very low. Specify a token with -token to avoid quota errors.")
 		fmt.Println("See https://help.github.com/en/articles/creating-a-personal-access-token-for-the-command-line.")
 	}
+	err := app.CreateWindow(&app.WindowOptions{
+		Width:  ui.Dp(400),
+		Height: ui.Dp(800),
+		Title:  "Gophers",
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
 	app.Main()
 }
 
@@ -141,16 +149,13 @@ func init() {
 	fonts.italic = mustLoadFont(goitalic.TTF)
 	fonts.mono = mustLoadFont(gomono.TTF)
 	go func() {
-		w, err := app.NewWindow(&app.WindowOptions{
-			Width:  ui.Dp(400),
-			Height: ui.Dp(800),
-			Title:  "Gophers",
-		})
-		if err != nil {
-			log.Fatal(err)
-		}
-		if err := newApp(w).run(); err != nil {
-			log.Fatal(err)
+		for w := range app.Windows() {
+			w := w
+			go func() {
+				if err := newApp(w).run(); err != nil {
+					log.Fatal(err)
+				}
+			}()
 		}
 	}()
 }