1. Binding written in xaml is useless; 2. Crash if adorned element is collapsed;

[Larry-Liang]

No description provided.

[JohanLarsson]

Not sure what you mean by #1 but guessing it is due to the adorner not being in the visual tree. Maybe post a sample?

2# Sounds like a bug.

Can you split it up into two issues?

[Larry-Liang]

Sorry for my laziness. Anyway, as for the 1st one, exactly, binding is invalid in xaml if its source is a relativesource or a concrete element(whenever elements are in adorner layer or not). However, I wrote bindings in code behind, they worked!

[Larry-Liang]

<Canvas>
                <Thumb
                    Name="thumb"
                    Canvas.Left="199"
                    Canvas.Top="204"
                    Width="80"
                    Height="30"
                    DragDelta="thumb_DragDelta">
                    <ad:Adornment.Content>
                        <Rectangle
                            Width="80"
                            Height="{Binding ElementName=thumb, Path=Width}"
                            ad:Adornment.Left="0"
                            ad:Adornment.Top="-110"
                            Fill="Red" />
                    </ad:Adornment.Content>
                </Thumb>

            </Canvas>

[JohanLarsson]

Try with x:Reference
This stuff is pretty messy but I think the adorners work the same way as for example tooltips.

[JohanLarsson]

I wrote UI-tests collapsing and restoring the adorned element but they fail to repro the bug. Do you have repro steps?