...
9: typedef void _EventCallback(Event event);
...

...
146: ui.window.onEvent = _handleEvent;
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207: void _handleEvent(String eventType, double timeStamp) {...}
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org.domokit.sky.shell E/chromium: [ERROR:dart_error.cc(16)] Unhandled exception:
                                                                 type '(String, double) => void' is not a subtype of type '_EventCallback' of 'value'.
                                                                 #0      Window.onEvent= (file:///src/flutter/engine/src/out/android_Release/gen/sky/bindings/Customwindow.dart:33)
                                                                 #1      FlutterBinding.FlutterBinding (packages/flutter/src/rendering/binding.dart:146)
                                                                 #2      WidgetFlutterBinding.WidgetFlutterBinding (packages/flutter/src/widgets/binding.dart:12)
                                                                 #3      WidgetFlutterBinding.ensureInitialized (packages/flutter/src/widgets/binding.dart:19)
                                                                 #4      runApp (packages/flutter/src/widgets/binding.dart:82)
                                                                 #5      main (/Users/ivbaranov/Projects/flutter/flutter/examples/fitness/lib/main.dart:165)