Remove window::Mode and introduce Settings::visible

Additionally, only show the window once one frame has been rendered to avoid blank flashes on Windows.

glutin/src/application.rs

@@ -54,13 +54,17 @@ where
         runtime.enter(|| A::new(flags))
     };
 
+    let should_be_visible = settings.window.visible;
+
     let context = {
-        let builder = settings.window.into_builder(
-            &application.title(),
-            application.mode(),
-            event_loop.primary_monitor(),
-            settings.id,
-        );
+        let builder = settings
+            .window
+            .into_builder(
+                &application.title(),
+                event_loop.primary_monitor(),
+                settings.id,
+            )
+            .with_visible(false);
 
         log::info!("Window builder: {:#?}", builder);
 
@@ -135,6 +139,7 @@ where
         receiver,
         context,
         init_command,
+        should_be_visible,
         settings.exit_on_close_request,
     ));
 
@@ -187,6 +192,7 @@ async fn run_instance<A, E, C>(
     mut receiver: mpsc::UnboundedReceiver<glutin::event::Event<'_, A::Message>>,
     mut context: glutin::ContextWrapper<glutin::PossiblyCurrent, Window>,
     init_command: Command<A::Message>,
+    should_be_visible: bool,
     exit_on_close_request: bool,
 ) where
     A: Application + 'static,
@@ -200,6 +206,7 @@ async fn run_instance<A, E, C>(
     let mut clipboard = Clipboard::connect(context.window());
     let mut cache = user_interface::Cache::default();
     let mut state = application::State::new(&application, context.window());
+    let mut visible = false;
     let mut viewport_version = state.viewport_version();
 
     application::run_command(
@@ -399,6 +406,12 @@ async fn run_instance<A, E, C>(
 
                 debug.render_finished();
 
+                if !visible && should_be_visible {
+                    context.window().set_visible(true);
+
+                    visible = true;
+                }
+
                 // TODO: Handle animations!
                 // Maybe we can use `ControlFlow::WaitUntil` for this.
             }