class WindowEx : public NoesisApp::Window
{
...
};

class DesignerMainWindow : public WindowEx
{
...
};

<Window
    x:Class="DesignerMainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006">
    <Grid/>
</Window>

			
auto symbol = Symbol("DesignerMainWindow");
			
if (Factory::IsComponentRegistered(symbol)) {
	if (auto component = DynamicPtrCast<WindowEx>(Factory::CreateComponent(symbol))) {
		component->SetIsActive(true);
		component->Show();
		return;
	}
}

auto root = Noesis::GUI::LoadXaml("Designer/DesignerMainWindow.xaml");
if (auto wnd = DynamicPtrCast<WindowEx>(root)) {
}