如何在wpf中使控件的大小与锚/船坞属性相等

I've read so many solutions this problem. every one of them fails to solve my problem. no matter what container I put the control into or what properties I set on the control/container it will not budge. I have a scroll viewer with a control within. I want it to resize with the window when the user resizes it at runtime. all I need is anchor=top, bottom, left, right. I don't understand why this is so elusive in WPF and why container objects and all kinds of property assignments need to be involved to accomplish what a single property can in Forms. but every solution to this problem still results in my control staying at exactly its design time size as the window is resized at runtime. what's the simple way to get a grip on dynamic control sizing in wpf?I've read so many solutions this problem. every