Use the AutoHideGroup.AutoHideType attached property:
<dxd:DockLayoutManager>
<dxd:LayoutGroup Orientation="Horizontal" x:Name="LayoutRoot">
<dxd:LayoutGroup Orientation="Vertical">
<dxd:LayoutPanel ItemWidth="200" dxd:AutoHideGroup.AutoHideType="Left"
Caption="Statuswort"
Padding="1">
<TextBox BorderThickness="0" />
</dxd:LayoutPanel>
<dxd:LayoutPanel ItemWidth="200" dxd:AutoHideGroup.AutoHideType="Left"
Caption="Steuerwort"
Padding="1">
<TextBox BorderThickness="0" />
</dxd:LayoutPanel>
<dxd:LayoutPanel ItemWidth="200" dxd:AutoHideGroup.AutoHideType="Left"
Caption="Übersicht"
Padding="1">
<TextBox BorderThickness="0" />
</dxd:LayoutPanel>
</dxd:LayoutGroup>
</dxd:LayoutGroup>
</dxd:DockLayoutManager>