initialize method
Starts the activity and watcher Widget.
Implementation
void initialize(Element element, bool replace) {
_watcher.initActivity(() {
_watcher.node = _html.call(this).node;
_watcher.node.styles = _styles?.call();
_watcher.node.init(element, replace);
onMount();
});
_watcher.watchActivity(() {
activity();
_update();
_controlState();
});
}