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Closable tab with tab item being a user control

I am working on a project in C# WPF. I have a tab container and I want to dynamically load different types of tabs into the tab container as the user requires. As an example I am doing something like the following:
tabContainer.Items.Add(new MyUserControl());
I want each tab to have a close button so the tab can be removed the container when the user no longer requires it.
I found this code project example but from what I can see you are a loading a user control which contains the xaml for the tab itself, not the tab content or am I missing something.
How can I load in my User Control into the tab container, but also have the tab closable.
Currently the tab that I am loading in uses some static binding to set the tab title using the following:
<TabControl x:Name="tabContainer" Grid.Column="2" Margin="10,45,0,0" RenderTransformOrigin="0.5,0.55" Grid.ColumnSpan="3">
<TabControl.Resources>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Header" Value="{Binding TabHeader}" />
</Style>
</TabControl.Resources>
</TabControl>
My user control then has a `public string TabHeader{get;set;} which gets set in the constructor depending on what constructor of my user control is used.

You will have to define the close Button yourself. You could for example do this in the HeaderTemplate of the TabItem:
<TabControl x:Name="tabContainer">
<TabControl.Resources>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Header" Value="{Binding TabHeader}" />
<Setter Property="HeaderTemplate">
<Setter.Value>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}" />
<Button Content="x" Click="Button_Click_2"
Tag="{Binding DataContext, RelativeSource={RelativeSource AncestorType=TabItem}}"/>
</StackPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</TabControl.Resources>
</TabControl>
The Tag property is bound to the UserControl in the Items collection which you can remove in the click event handler of the Button, like this:
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
tabContainer.Items.Add(new MyUserControl());
}
private void Button_Click_2(object sender, RoutedEventArgs e)
{
Button button = sender as Button;
tabContainer.Items.Remove(button.Tag);
}
}

If you want to add a close button to each tab, that would be in the TabItem style ControlTemplate. Normally you'd specify the data context (i.e. the data only that's driving the content) in Content and then specify the look in ContentTemplate. If your Content is a UserControl then you don't specify the ContentTemplate since a UserControl knows how to draw itself.

For my sins, I've added close-tab buttons to the WPF TabControl. I ended up putting the close button in the ItemTemplate. Here's a minimal version that works with the way you're populating the TabControl and the header content:
<TabControl
>
<TabControl.Resources>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Header" Value="{Binding TabHeader}" />
</Style>
</TabControl.Resources>
<TabControl.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<Label
Content="{Binding}"
Grid.Column="0"
/>
<Button
VerticalAlignment="Center"
Grid.Column="1">
<Path
Data="M 0, 0 L 12, 12 M 12,0 L 0,12"
Stroke="Red"
StrokeThickness="2"
Width="12"
Height="12"
/>
</Button>
</Grid>
</DataTemplate>
</TabControl.ItemTemplate>
<local:UserControl1 TabHeader="First Item" />
<local:UserControl1 TabHeader="Second Item" />
</TabControl>

Style usercontrol child by name in XAML?

I saw the following code in stackoverflow:
<UserControl x:Class="WpfApplication3.UserControl1"
x:Name="Uc1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<UserControl.Resources>
<Style TargetType="Label">
<Setter Property="Foreground"
Value="{Binding Foreground, ElementName=Uc1, Mode=OneWay}"/>
</Style>
</UserControl.Resources>
<Grid>
<Label Content="Label 1"/>
<Label Content="Label 2"/>
</Grid>
</UserControl>
Question: I now wonder if I can target a specific label inside my usercontrol.resources for styling. Is it possible inside my userControl? If so then how?

A Style without a Key will be applied to all instances of the Target Type within the scope.
Give the style a Key, like,
<Style TargetType="Label" x:Key="MyLabel">
and then use the Key as following
<Label Content="Label 1" Style="{StaticResource MyLabel}" />
<!--Will not apply the style to Label 2-->
<Label Content="Label 2"/>
Edit:
I read your question again, seems you want to reference a Target from a Style, not reference a Style from a Target. Is that right? It sounds unnatural, it is like wanting to know the name of an instance of a derived class, from the base class.

AutomationElement for WPF ToggleButton - have ClassName Button

I am using ToggleButtons in the ToolBar and I want to get and use them in the UI Automation tests, but when I check AutomationElement.Current for these buttons, its ClassName property is Button, while I would expect ToggleButton
The xaml is not starightforward, so I mention it here :
<ToolBar ItemsSource="{Binding}"/>
for the type that's in the ItemsSource I have a DataTemplate:
<DataTemplate DataType="{x:Type myViewModelType}">
<ContentPresenter Content="{Binding}" ContentTemplate="{StaticResource MyToolBarElementTemplate}">
<ContentPresenter.Resources>
<Style TargetType="{x:Type ToggleButton}" BasedOn="{StaticResource ThisStyleSetsWidthAndHeight}"/>
</ContentPresenter.Resources>
</ContentPresenter>
</DataTemplate>
the style is defined as follows:
<Style TargetType="{x:Type ButtonBase}" x:Key="ThisStyleSetsWidthAndHeight">
<Setter Property="styles:AttachedProperties.ContentWidth" Value="32"/>
<Setter Property="styles:AttachedProperties.ContentHeight" Value="32"/>
</Style>
and the content template looks like this:
<DataTemplate x:Key="MyToolBarElementTemplate" DataType="{x:Type myViewModelType}">
<ToggleButton x:Name="AutomationIdThatIGetOk">
...
</ToggleButton>
</DataTemplate>
I am a bit new to Automation Framework, I guess it has to do with all these templates and styles, but is there any way to get the proper AutomationPeer instance created for this ToggleButton?

...but when I check AutomationElement.Current for these buttons, its ClassName property is Button, while I would expect ToggleButton
Your expectation is wrong because the ToggleButtonAutomationPeer class actually returns the string "Button" from its GetClassNameCore() method: https://referencesource.microsoft.com/#PresentationFramework/src/Framework/System/Windows/Automation/Peers/ToggleButtonAutomationPeer.cs,a58abe77888c16cd
So you are getting the proper instance.

How to change XAML elemen't template from code-behind?

I have next button's style defined in resources:
<Style x:Key="OKBtn" TargetType="{x:Type Button}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Grid>
<Rectangle .../>
<TextBlock x:Name="Text" ..>
<Run Language="en-en" Text="OK"/>
</TextBlock>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
And I want in some specified case from code change Button's text.
I.e. change "OK" (<Run Language="en-en" Text="OK"/>) to "Accept".
How can I do that?
Is it possible to access this TextBlock "Text" and change content exactly for my one button, but not for all OK buttons?
My button:
<Button x:Name="OkButton" Style="{DynamicResource OKBtn}" />

You can borrow some props from template Template, for example Tag property. So the TextBlock text in the ControlTemplate should be like this.
<Run Language="en-en" Text="{Binding RelativeSource={RelativeSource Mode=TemplatedParent}, Path=Tag}"/>
And you can change the button caption by setting it's Tag property.
OkButton.Tag = "Accept";
And for not set all button texts manually you can create some ValueConverter to set TextBlock text in the ControlTemplate to the "Ok" whenever Tag property is empty.

At first, you should declare ContentPresenter to show any object in your Content property of Button control.
<Style x:Key="OkBtn" TargetType="Button">
<Setter Property="ContentTemplate">
<Setter.Value>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Rectangle/>
<ContentPresenter Content="{Binding Path=Content, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Button}}}"></ContentPresenter>
</StackPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
Then, it is possible to set another Content by using code behind or binding:
By code behind:
okButton.Content="desirableText";
By binding:
<Button x:Name="OkButton" Style="{DynamicResource OKBtn}" Content="{Binding FooText}" />
private string fooText;
public string FooText
{
get { return fooText; }
set
{
fooText = value;
OnPropertyChanged("FooText");
}
}

Using BasedOn and Trigger to manipulate nested property in parent Style

We have a file of standard styles. One style, SectionGroup, we use on all our GroupBox elements. It has a custom template which uses a Border to put an underline below the header, among other things.
On one page, we have a checkbox next to a GroupBox header; when the user unchecks the checkbox, the contents of the GroupBox hide (visibility collapsed) and the header remains. Unfortunately the underline under the header then looks ugly; we also want to hide this.
I've given it my best attempt, so the parent SectionGroup style now looks like this:
<Style x:Key="SectionGroup" TargetType="GroupBox">
<Style.Resources>
<Thickness x:Key="HeaderBorderThickness">0,0,0,1</Thickness>
</Style.Resources>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="GroupBox">
<Grid Margin="0">
...
<Border Grid.Row="0" BorderThickness="{DynamicResource HeaderBorderThickness}" >
<TextBlock Text="{Binding Header, RelativeSource={RelativeSource AncestorType=GroupBox}}"/>
</Border>
...
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
By defining the HeaderBorderThickness resource and using it as a DynamicResource, I can override it in my page (as explained in this answer):
<GroupBox>
<GroupBox.Style>
<Style TargetType="GroupBox" BasedOn="{StaticResource SectionGroup}">
<Style.Resources>
<Thickness x:Key="HeaderBorderThickness">0,0,0,0</Thickness>
</Style.Resources>
<!-- TODO triggers here.. -->
</Style>
</GroupBox.Style>
<GroupBox.Header>Section One</GroupBox.Header>
...contents...
</GroupBox>
So indeed, by redefining a Thickness of the same key, the DynamicResource works as expected and there is no underline on the header.
Now I need to toggle it based on a trigger/binding. I'm pretty new to this, but elsewhere in this page I have figured out to do stuff like this:
<Grid Visibility="{Binding Path=FooBoolean, Converter={StaticResource BooleanToVisibility}}">
I think there's a little more magic involved in our viewmodel class (followed the example of existing bindings & properties), but it works.
Now the question is -- how do I bind the boolean value in FooBoolean, to the HeaderBorderThickness resource value? Or what other means can I use to accomplish my goal?

It seems to me that you could do this in a much more WPF way with a DataTrigger, perhaps something like this:
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<TextBlock Text="{Binding Header, RelativeSource={RelativeSource AncestorType=
GroupBox}}"/>
<Rectangle Grid.Row="1" Height="1" Margin="0,2,0,0" Fill="Black">
<Rectangle.Style>
<Style>
<Setter Property="Rectangle.Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{IsChecked, ElementName=YourCheckBox}"
Value="False">
<Setter Property="Rectangle.Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
</Rectangle.Style>
</Rectangle>
</Grid>
This method enables you to set the Width, Height, Padding and whatever other properties of the line. If you can't access the CheckBox directly from the Style, then you could try adding a bool property to bind to both the Checkbox.IsChecked property and the DataTrigger.Binding property. Or just manage the Rectangle.Visibility in your own method.