I have a groupbox that contains nested stack panels that aren't filling in the groupbox entirely. I would like to have all the stackpanels evenly spaced out filling in the entire groupbox. I have attempted changing the VerticalContentAlignment to Stretch for the groupbox, but that does not work.
<GroupBox>
<StackPanel>
<StackPanel Orientation="Horizontal">
<Label Content="Test1" />
<Label Content="Test2"/>
</StackPanel>
<StackPanel Orientation="Horizontal">
<Label Content="Test3" />
<Label Content="Test4"/>
</StackPanel>
</StackPanel>
</GroupBox