I do not know what I am doing wrong here. In the XAML below, the Border does not fill the available space on the tabItem (just lots of whitespace). How do I fill the entire tab page?
<TabControl>
<TabItem Header="Plant State">
<Border Background="Red" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"></Border>
</TabItem>
</TabControl>
I figured this out with the help of Matt Hamilton. This actually works fine if you are using a regular TabControl (default Template).
I am using a xaml "theme" that alters the default control template. That is causing the layout to fail, so I will have to investigate and figure out what is wrong.