Can't see TabItem content in Expression Blend - wpf

Question

So here is my problem. I have a WPF application basically composed of a TabControl with many TabItems. I have each TabItem declared in separated classes, and what I do is insert them into the TabControl of the MainWindow like this:
<TabControl x:Name="tabCtrl" Grid.Column="2" Margin="89.765,29.697,89.766,33.697"
Style="{DynamicResource TabControlStyle1}" TabStripPlacement="Left"
SelectionChanged="tabCtrl_SelectionChanged">
<TabControl.Background>
<SolidColorBrush Color="#FFF9F9F9" Opacity="0.6"/>
</TabControl.Background>
<local:WelcomeTab Width="Auto" Height="Auto" x:Name="welcomeTab"/>
<local:Step1Tab Width="Auto" Height="Auto" x:Name="step1Tab"/>
<local:Step2Tab Width="Auto" Height="Auto" x:Name="step2Tab"/>
<local:Step3Tab Width="Auto" Height="Auto" x:Name="step3Tab"/>
<local:Step4Tab Width="Auto" Height="Auto" x:Name="step4Tab"/>
</TabControl>
I use Expression Blend to edit the tabs, and as I'm using this method, I have to edit each tab in their own class. The problem is that when I want to do it, I must do it directly in the XAML because all I see of the TabItem is the header.
The XAML of this tab, for example, is something like this:
<TabItem x:Class="Foo.Step1Tab"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
xmlns:Microsoft_Windows_Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero"
xmlns:p="clr-namespace:Foo.Properties"
x:Name="step1Tab" IsEnabled="true"
IsManipulationEnabled="True"
d:DesignHeight="300" d:DesignWidth="300" Header="{x:Static p:Resources.step1Tab}" Style="{DynamicResource TabItemStyle1}">
<Content of the tab>
</TabItem>
Is there anything I can do to be able to see the elements of the tab and manipulate them?