Drag Adorner at wrong position on High DPI screens

Description When dragging an item from a ListBox the dragged item is shown at a wrong position offset to the lower right. This only occurs on a High DPI screens such as Notebooks.

Repro This can be reproduced with the simplest of all programs:

<Window x:Class="DragItemScreenPositionIssue.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        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"
        xmlns:dd="clr-namespace:GongSolutions.Wpf.DragDrop;assembly=GongSolutions.Wpf.DragDrop"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <ListBox dd:DragDrop.IsDropTarget="True" dd:DragDrop.IsDragSource="True"
                 dd:DragDrop.UseDefaultEffectDataTemplate="True" dd:DragDrop.UseDefaultDragAdorner="True">
            <ListBoxItem>ListBox Item #1</ListBoxItem>
            <ListBoxItem>ListBox Item #2</ListBoxItem>
            <ListBoxItem>ListBox Item #3</ListBoxItem>
        </ListBox>
    </Grid>
</Window>

Versions It is a regression between release 2.3.2 and 2.4.0. Tested with .NET Framework 4.8 and 4.5.2 (to rule out fix for issue #363).

[punker76]

@angus42 I found a solution. Hopefully it’s working without any issue with the GetCurrentPos…

[angus42]

Agreed that using the path without the Canvas is better XAML. Still had to do a little scale transformation by 50% even with the Stretch=“Uniform”. But with that and the develop branch it now works under all situations I can come up with. Thx.