Add a checkbox to quit on disconnect

src/app.rs

@@ -211,8 +211,12 @@ impl ApplicationHandler<UserEvent> for Application {
                 );
                 self.open(event_loop, Box::new(p2));
             }
-            UserEvent::Quit => {
-                event_loop.exit();
+            UserEvent::Quit(sim_id) => {
+                self.viewports
+                    .retain(|_, viewport| viewport.app.sim_id() != sim_id);
+                if !self.viewports.contains_key(&ViewportId::ROOT) {
+                    event_loop.exit();
+                }
             }
         }
     }
@@ -401,7 +405,7 @@ pub enum UserEvent {
     OpenDebugger(SimId),
     OpenInput,
     OpenPlayer2,
-    Quit,
+    Quit(SimId),
 }
 
 pub enum Action {