Adorners render behind MahApps.Metro flyout

[pribnoda]

I wasn't absolutely sure which repository to add this issue in since this seems to be a corner case between MahApps.Metro and GongSolutions.WPF.DragDrop.

What steps will reproduce this issue?

Try to create a drag/drop interface with drag/effect adorners on a MahApps flyout. Instead of showing on top, they'll render behind the flyout and flyout overlay (if modal).

You can see the adorners peek out behind the right side of the flyout:

Expected outcome

Adorners are on top of current flyout content

Repo

Quick demo of the error: https://github.com/pribnoda/DragAdornerTest

Environment

• GongSolutions.WPF.DragDrop v2.1.0
• MahApps.Metro v1.6.5
• Windows OS 10 x64
• Visual Studio 2019
• .NET Framework 4.7.2