to keep the things simple (and show an additional issue :)) I made a short video showing this "extra tag".
By the way - the "additional issue" is that grid sometimes does not show it's properties in the properties pane.
After switching to Shared / Design and back to source the properties are visible.
This happens occasionally - sometimes it works for hours - sometimes each "unselect" and select again results in missing properties.
By the way - this was just one property - it becomes (of course) more worse when the are more columns - properties.
And - just found out today - RadFileExplorer does the same thing.
Some Attributes get extended to "inline parameters".