TabControl - Align TabItems correctly if free space dominates - wpf

Question

I have a customized TabControl:
<Window x:Class="WpfApplication2.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<Style TargetType="TabControl">
<Setter Property="Background" Value="Transparent" />
<Setter Property="BorderThickness" Value="0" />
<Setter Property="TabStripPlacement" Value="Bottom" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TabControl">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid Grid.Row="1" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<TabPanel Grid.Column="0" Panel.ZIndex="1" IsItemsHost="True" Background="Transparent" />
<ItemsControl Grid.Column="1">
<ItemsControl.Items>
<Button Height="50">DOMINATES</Button>
</ItemsControl.Items>
</ItemsControl>
</Grid>
<ContentPresenter Grid.Row="0" ContentSource="SelectedContent" />
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Border Background="LightCyan" Padding="20,0">
<TextBlock SnapsToDevicePixels="True" Text="{TemplateBinding Header}" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<TabControl>
<TabItem Header="TEST 123">
<TextBlock>1</TextBlock>
</TabItem>
<TabItem Header="TEST 456">
<TextBlock>2</TextBlock>
</TabItem>
</TabControl>
</Window>
Beside the TabItems other controls are placed - which are much higher than the TabItems. How can i stretch the TabItems and place the TextBox in the middle (so that the fill the area)? Can i adjust the Padding dynamically?
http://goo.gl/xcYOY3 The red marked area should be filled and the TextBox centered. Is this possible?
Thx :)
Solution
<Window x:Class="WpfApplication2.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<Style TargetType="TabControl">
<Setter Property="Background" Value="Transparent" />
<Setter Property="BorderThickness" Value="0" />
<Setter Property="TabStripPlacement" Value="Bottom" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TabControl">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<ContentPresenter Grid.ColumnSpan="2" Grid.Column="0" Grid.Row="0" ContentSource="SelectedContent" />
<TabPanel Panel.ZIndex="1" Grid.Row="1" Grid.Column="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" IsItemsHost="True" Background="Transparent" />
<ItemsControl Grid.Row="1" Grid.Column="1" VerticalAlignment="Bottom">
<ItemsControl.ItemContainerStyle>
<Style TargetType="FrameworkElement">
<Setter Property="HorizontalAlignment" Value="Stretch"></Setter>
</Style>
</ItemsControl.ItemContainerStyle>
<Button Background="LightGray" Height="70" BorderThickness="0">DOMINATES</Button>
</ItemsControl>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Grid Background="LightCyan" Height="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type TabPanel}}, Path=ActualHeight}">
<TextBlock SnapsToDevicePixels="True" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="20,0" Text="{TemplateBinding Header}" ></TextBlock>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<TabControl>
<TabItem Header="TEST 123">
<TextBlock >1</TextBlock>
</TabItem>
<TabItem Header="TEST 456">
<TextBlock >2</TextBlock>
</TabItem>
</TabControl>
</Window>

Answer 1

I have edited your template As per you image ..please run this xaml code separately.
<Window.Resources>
<Style TargetType="TabControl">
<Setter Property="Background" Value="Transparent" />
<Setter Property="BorderThickness" Value="0" />
<Setter Property="TabStripPlacement" Value="Bottom" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TabControl">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="50"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<ContentPresenter Grid.ColumnSpan="2" Height="50" Grid.Row="0" HorizontalAlignment="Center" VerticalAlignment="Center" ContentSource="SelectedContent" />
<Grid Grid.Row="1" Grid.Column="0" Background="LightCyan">
<TabPanel Panel.ZIndex="1" HorizontalAlignment="Center" VerticalAlignment="Center" IsItemsHost="True" Background="Transparent" />
</Grid>
<ItemsControl Grid.Row="1" VerticalAlignment="Bottom" Grid.Column="1">
<ItemsControl.ItemContainerStyle>
<Style TargetType="FrameworkElement">
<Setter Property="HorizontalAlignment" Value="Stretch"></Setter>
<Setter Property="Height" Value="50"></Setter>
</Style>
</ItemsControl.ItemContainerStyle>
<Button Background="LightGray" BorderThickness="0">DOMINATES</Button>
</ItemsControl>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Grid Background="LightCyan" >
<TextBlock SnapsToDevicePixels="True" Margin="5,0,5,0" >
<ContentPresenter x:Name="ContentSite" HorizontalAlignment="Center" VerticalAlignment="Center" ContentSource="Header" RecognizesAccessKey="True"/>
</TextBlock>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<TabControl>
<TabItem Header="TEST 123">
<TextBlock >1</TextBlock>
</TabItem>
<TabItem Header="TEST 456">
<TextBlock >2</TextBlock>
</TabItem>
</TabControl>
and output from above code is http://prntscr.com/2yc51f
Update
<Style TargetType="TabControl">
<Setter Property="Background" Value="Transparent" />
<Setter Property="BorderThickness" Value="0" />
<Setter Property="TabStripPlacement" Value="Bottom" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TabControl">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="50"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<ContentPresenter Grid.ColumnSpan="2" Height="50" Grid.Row="0" HorizontalAlignment="Center" VerticalAlignment="Center" ContentSource="SelectedContent" />
<TabPanel Panel.ZIndex="1" Grid.Row="1" Grid.Column="0" HorizontalAlignment="Center" VerticalAlignment="Center" IsItemsHost="True" Background="Transparent" />
<ItemsControl Grid.Row="1" VerticalAlignment="Bottom" Grid.Column="1">
<ItemsControl.ItemContainerStyle>
<Style TargetType="FrameworkElement">
<Setter Property="HorizontalAlignment" Value="Stretch"></Setter>
<Setter Property="Height" Value="50"></Setter>
</Style>
</ItemsControl.ItemContainerStyle>
<Button Background="LightGray" BorderThickness="0">DOMINATES</Button>
</ItemsControl>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Grid Background="LightCyan" Height="50">
<TextBlock SnapsToDevicePixels="True" HorizontalAlignment="Center" VerticalAlignment="Center" Margin="5,0,5,0" Text="{TemplateBinding Header}" ></TextBlock>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>