Listview doesnt use unused space when expander is closed

Hello,

I got in a window a listview and an expander parallel. The expander got also some controls in it.

When I remove the expander the listview fills the content of the window. But when the expander is closed the listview isnt using the unused space.

How can I tell the listview to use the unused space when the expander ist closed.

Have anyone ideas?

<DockPanel><ListView DockPanel.Dock="Left" HorizontalAlignment="Stretch"></ListView><Expander x:Name="expander" ExpandDirection="Right" DockPanel.Dock="Right"><some controls /></Expander></DockPanel>

greetings