How to use left over space in wpf tab items row

Question

Upper part of TabControl consists of TabItem controls. Is there a way to reuse remaining space there to put some WPF content?

I think I could use a "fake" TabItem with different styling and put my stuff in TabItem.Header but I was hoping there's a better way.

Solution

Based on the answer below, I got the desired behavior by wrapping TabPanel in the template below within e.g. StackPanel and adding my additional content after it.

<StackPanel Orientation="Horizontal">
   <TabPanel 
    Grid.Row="0"
    Panel.ZIndex="1" 
    Margin="0,0,4,-1" 
    IsItemsHost="True"
    Background="Transparent" />
    <TextBlock>Foo</TextBlock>
</StackPanel>

Answer 1

You can use a template and make it do whatever you want, that is the power of WPF. Here is a nice article on customizing the TabControl and the TabItem controls.

< EDIT Adding code for TabControl template from Switch On The Code article>

<Style  TargetType="{x:Type TabControl}">
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="{x:Type TabControl}">
        <Grid>
          <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
          </Grid.RowDefinitions>
          <TabPanel 
             Grid.Row="0"
             Panel.ZIndex="1" 
             Margin="0,0,4,-1" 
             IsItemsHost="True"
             Background="Transparent" />
          <Border 
             Grid.Row="1"
             BorderBrush="Black" 
             BorderThickness="1" 
             CornerRadius="0, 12, 12, 12" >
            <Border.Background>
              <LinearGradientBrush>
                <GradientStop Color="LightBlue" Offset="0" />
                <GradientStop Color="White" Offset="1" />
              </LinearGradientBrush>
            </Border.Background>
            <ContentPresenter ContentSource="SelectedContent" />
          </Border>
        </Grid>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>

all you have to do is add your content to the Template, the part that holds the tab items is the <TabControl>

Answer 2

I tried a different way, which was to create another grid that occupies the same space as the TabControl, ie both are in Grid.Row=0. I have bound the grid height to the height of the first tab so if the tabs change height the other controls will remain centered. I set MinWidth on the window so the controls dont overlap the tabs.

Paste this code into a new WPF Window...

<Window x:Class="MainWindow"
    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"
    mc:Ignorable="d"
    Title="MainWindow" Height="306" Width="490" MinWidth="300">
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="*" />
        <RowDefinition Height="Auto" />
    </Grid.RowDefinitions>
    <TabControl Grid.Row="0" x:Name="tabControl">
        <TabItem x:Name="tabItem" Header="TabItem" Height="50">
            <Grid Background="#FFE5E5E5"/>
        </TabItem>
        <TabItem Header="TabItem">
            <Grid Background="#FFE5E5E5"/>
        </TabItem>
    </TabControl>

    <Grid Grid.Row="0" Height="{Binding ActualHeight, ElementName=tabItem}" 
           VerticalAlignment="Top" Margin="0,2,0,0">
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right" 
                    VerticalAlignment="Center" Margin="20,0">
            <TextBlock VerticalAlignment="Center" Margin="10,0" FontSize="16" 
                       Foreground="Red" FontFamily="Calibri">My Text</TextBlock>
            <Button Content="My Button" />
        </StackPanel>
    </Grid>

  </Grid>
</Window>

...and you will get this: