I'm very new to WPF programming, but I thought I would see if I could gain some functionality buy converting one of my old Win Forms. Right of the go I have a question. I have to treeview controls inside a dockpanel. I would like each to take up half the panel. I tried using Width="50%" like I would with a web app, but that didn't work. I could set them in the code behind, but it seems like there should be a way to specify the width of the treeview is half that of the parent dock panel in XAML.