I hear you. I also am missing an out of the box solution in WPF for this.
Sometimes you want some code to be executed after all the child controls are loaded.
Put this in the constructor of the parent control
Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(() => {code that should be executed after all children are loaded} ));
Helped me a few times till now.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…