WPF复合应用程序 - 选项卡区域 - 视图无法获得焦点

I'm just starting to use the composite application libraries for WPF. In my shell I have a region in a tabcontrol that is used to display different types of views. I also have a toolbar with buttons hooked up to commands, for example save. The commands are bound in my views, and the views have the canExecute and execute methods. I'm just starting to use the composite applicat