As you know you can\'t bind an Event directly to a command without a behaviour:
Thats a version I am using for a Button-command in a similar situation (Button in DataGridRow, Command on DataGrid should be invoked by the Button and I need the DataContext of the row in my command). You would have to use the command of the InvokeCommandAction of the doubleClick-trigger instead, but then it should work as well, I suppose.
Good luck!