Detect if a tab was closed by user (not dragged out)

[BornToBeRoot]

Hello,

you have a great control...

I try to detect if a user closed the tab via the button in the header and fire a command on the content viewmodel.

I tried to implement IDisposable with CollectionChanged on the source list, but this will only work on the main TabControl and is always fired when dragging out a tab.

Any ideas?

Thanks!