ASP.NET 101 Reminder 2: ListItem[] is an array of Reference Types

..which means that if you fill one ListControl with the ListItem[] array, and then fill another ListControl with the same array, BOTH DropDownLists will be updated if you modify any ListItem (such as selecting it: ListItem.Selected = true;)

If you think of a ListControl as its HTML equivalent then this may be a bit confusing and bug-prone (and indeed, once rendered as HTML the controls are no longer in sync, it only happens server-side), but from an OO perspective it does make perfect sense.

It just makes me wish for easier and generic deep cloning of collections of objects…. Sigh.