Xaml do not load UserControl from ViewModel object?

Answer 1

you should create a template for your viewmodel in your app.xaml file like this

 <DataTemplate DataType="{x:Type simpleModel:TextBoxInputViewModel}">
        <myView:TextBoxInputControl />
    </DataTemplate>

where simpleModel is the namespace of TextBoxInputViewModel, and TextBoxInputControl is the user control you want to show and myView is the namespace of that user control.

Answer 2

The problem is that ItemSource is a collection, where as you're binding it to a property that is just one value. The error in the Output window that you're seeing is likely related to this.

Instead of returning a UserControl directly from your View Model, it would be better to return another View Model that represents the contents of the tab, and use templates to display that content. If you need it to be more dynamic than choosing the template based on the Type of the View Model, look into setting TabControl.ContentTemplateSelector. This needs to be set to a class that derives from DataTemplateSelector. You can use this class to decide which template to load based on the object bound to that tab.