Hi Vanya,
I think we don't understand us.
In your sample, the image is indented too.
What I want to do is to replace the builtin indent system, to manage it with my custom ImageColumn. Note this may (if possible) not erase the existing ToggleButton to manage IsExpanded.
Or to simplify, mark the child relation with the same behavior as the TreeView.
Actual Result / Expected result (photoshoped)

