MouseEvent(
String type,
{Window view,
int detail: 0,
int screenX: 0,
int screenY: 0,
int clientX: 0,
int clientY: 0,
int button: 0,
bool canBubble: true,
bool cancelable: true,
bool ctrlKey: false,
bool altKey: false,
bool shiftKey: false,
bool metaKey: false,
EventTarget relatedTarget}
)

Not documented.