Avalonia/samples/IntegrationTestApp/Pages/DragDropPage.axaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
             x:Class="IntegrationTestApp.Pages.DragDropPage">
  <DockPanel>
    <StackPanel DockPanel.Dock="Top" Orientation="Horizontal" Margin="4">
      <Button Name="ResetDragDrop" Click="ResetDragDrop_Click" Margin="0,0,8,0">Reset</Button>
      <TextBlock VerticalAlignment="Center">Drop Position: </TextBlock>
      <TextBlock Name="DropPosition" VerticalAlignment="Center" Margin="4,0"/>
      <TextBlock VerticalAlignment="Center" Margin="8,0,0,0">Status: </TextBlock>
      <TextBlock Name="DragDropStatus" VerticalAlignment="Center" Margin="4,0"/>
    </StackPanel>

    <!-- Use a Grid with row definitions to create offset from window origin -->
    <!-- The top spacer ensures the drag/drop controls are NOT at (0,0) -->
    <Grid RowDefinitions="100,*">
      <!-- Spacer row to offset controls from window origin -->
      <Border Grid.Row="0" Background="LightGray">
        <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center"
                   Text="Spacer (100px) - Controls below are offset from window origin"/>
      </Border>

      <!-- Drag and Drop test area -->
      <Grid Grid.Row="1" ColumnDefinitions="*,*" Margin="20">
        <!-- Drag Source -->
        <Border Name="DragSource"
                Grid.Column="0"
                Background="CornflowerBlue"
                Margin="10"
                CornerRadius="8"
                AutomationProperties.AccessibilityView="Content"
                PointerPressed="DragSource_PointerPressed">
          <TextBlock HorizontalAlignment="Center"
                     VerticalAlignment="Center"
                     Text="Drag Source"
                     Foreground="White"
                     FontWeight="Bold"/>
        </Border>

        <!-- Drop Target -->
        <Border Name="DropTarget"
                Grid.Column="1"
                Background="LightGreen"
                Margin="10"
                CornerRadius="8"
                AutomationProperties.AccessibilityView="Content"
                DragDrop.AllowDrop="True">
          <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
            <TextBlock Text="Drop Target"
                       HorizontalAlignment="Center"
                       FontWeight="Bold"/>
            <TextBlock Name="DropTargetText"
                       HorizontalAlignment="Center"
                       Text="Drop items here"/>
          </StackPanel>
        </Border>
      </Grid>
    </Grid>
  </DockPanel>
</UserControl>