Support rebinding gamepad inputs

src/window.rs

@@ -18,4 +18,7 @@ pub trait AppWindow {
     fn handle_key_event(&mut self, event: &KeyEvent) {
         let _ = event;
     }
+    fn handle_gamepad_event(&mut self, event: &gilrs::Event) {
+        let _ = event;
+    }
 }