свойство onDragStart
override
Поток событий dragstart, обрабатываемых этим Window.
Реализация
Stream<MouseEvent> get onDragStart => Element.dragStartEvent.forTarget(this);
© 2012 the Dart project authors
Licensed under the BSD 3-Clause "New" or "Revised" License.
https://api.dart.dev/stable/2.19.6/dart-html/Window/onDragStart.html
