Rerwite everything to share an egui context

src/window.rs

@@ -1,9 +1,9 @@
 use std::sync::Arc;
 
 pub use about::AboutWindow;
-use egui::{Ui, ViewportBuilder, ViewportId};
-pub use game::GameWindow;
-pub use game_screen::DisplayMode;
+use egui::{Ui, ViewportBuilder};
+pub use game::{ChildWindow, GameWindow};
+pub use game_screen::{DisplayMode, GameScreen};
 pub use gdb::GdbServerWindow;
 pub use hotkeys::HotkeysWindow;
 pub use input::InputWindow;
@@ -28,7 +28,6 @@ mod utils;
 mod vip;
 
 pub trait AppWindow {
-    fn viewport_id(&self) -> ViewportId;
     fn sim_id(&self) -> SimId {
         SimId::Player1
     }
@@ -40,7 +39,6 @@ pub trait AppWindow {
     fn on_init(&mut self, args: InitArgs) {
         let _ = args;
     }
-    fn on_destroy(&mut self) {}
     fn handle_key_event(&mut self, event: &KeyEvent) -> bool {
         let _ = event;
         false