emberjs/ember.js — pull request #1554 by dagda1 (2012-11-20 13:30:26+00:00)
Title: Hook to Override default toggle visibility in _isVisibleDidChange

At the moment there is no way apart from overriding the whole of _isVisibleDidChange to supply your own custom animations for when the view's isVisible property changes:
```
_isVisibleDidChange: Ember.observer(function() {
var $el = this.$();
if (!$el) { return; }

var isVisible = get(this, 'isVisible');

$el.toggle(isVisible);

if (this._isAncestorHidden()) { return; }

if (isVisible) {
this._notifyBecameVisible();
} else {
this._notifyBecameHidden();
}
}, 'isVisible'),```