✅ WPF Custom control should have contents as DockPanel, but it shows up at runtime as ScrollViewer

<Base:AbstractVisualConversationTabCtrl
    x:Class="BestChat.IRC.Global.View.Ctrls.ConversationViewCtrl"
    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"
    xmlns:local="clr-namespace:BestChat.IRC.Global.View.Ctrls"
    xmlns:Base="clr-namespace:BestChat.GUI.Ctrls;assembly=BestChat.GUI.Ctrls"
    xmlns:data="BestChat.Platform.Conversations;Assembly=BestChat.Platform.Conversations"
    mc:Ignorable="d"
    xmlns:CalcBinding="clr-namespace:CalcBinding;assembly=CalcBinding">
    <Base:AbstractVisualConversationTabCtrl.Resources>
        <Style
            x:Key="ChkBoxStyle"
            TargetType="CheckBox"
            BasedOn="{StaticResource {x:Static ToolBar.ToggleButtonStyleKey}}" />
    </Base:AbstractVisualConversationTabCtrl.Resources>
    <DockPanel>
        <WrapPanel
            x:Name="wrapDataBar"
            DockPanel.Dock="Top" />
        <Border
            Background="Black" />
    </DockPanel>
</Base:AbstractVisualConversationTabCtrl>