ToolWindows added by Prism don't inherit Language property

Hi Phil,

Thanks for the sample.  The problem here seems to be based on how ItemsControls work (and DockSite mimics ItemsControl in scenarios like MVVM and Prism).  I was able to reproduce the same thing by making a simple ItemsControl like this in your sample:

public class TestItemsControl : ItemsControl {
	protected override bool IsItemItsOwnContainerOverride(object item) {
		return (item is SimpleToolWindow);
	}
	protected override System.Windows.DependencyObject GetContainerForItemOverride() {
		return new SimpleToolWindow();
	}
}

Then I put an instance of that in the window like this:

<wpfApplication1:TestItemsControl>
	<sys:String>test</sys:String>
	<sys:String>test</sys:String>
</wpfApplication1:TestItemsControl>

You'll see the same sort of thing occur where Language doesn't inherit down.  It must not cross the data item boundary.

As a workaround, I'd probably suggest you handle the DockSite.WindowRegistered event and in that, set up a Binding to bind the e.Window's Language property to the main window's Language property.