OK, I want to create a control that is like a Stackpanel with TextBlock on the left, something like:

The TextBlock need to be editable. So, the question is from whom I need to inherit to make that since cannot from Stackpanel?
That is basically a HeaderedItemsControl with a custom Template.
The template could be a Grid with two columns, one containing a rotated ContentPresenter which is bound to the header properties, on the right you would have an ItemsPresenter for the items.
e.g.
<Style TargetType="HeaderedItemsControl"> <!-- Implicitly applied --> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="HeaderedItemsControl"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto"/> <ColumnDefinition /> </Grid.ColumnDefinitions> <ContentPresenter ContentSource="Header"> <ContentPresenter.LayoutTransform> <RotateTransform Angle="-90"/> </ContentPresenter.LayoutTransform> </ContentPresenter> <ItemsPresenter Grid.Column="1"/> </Grid> </ControlTemplate> </Setter.Value> </Setter> </Style> <HeaderedItemsControl Header="Lorem Ipsum" ItemsSource="ABCDEF"/> TemplateBindings