ZK-2035. (The issue was not fixed properly in my opinion)
- click panel button to collapse
An error in browser console
TypeError: p is null; can't access its "getHflex" property
No error in browser console
Collapsing a panel triggers an animation, before the animation finished the widget is invalidated.
The afterAnima_ will be called after animation. But the widget is detached hence no parent.
Avoid calling invalidate if an animation is included in a action.
Or check this.desktop in afterAnima_