Sometimes I would like to have a custom scope that shows the files that are
part of an existing changelist.
I imagine I could select a changelist from the "Changes" view, and have an
context menu action "Show as custom scope".
However, I don't know of a clean way to delete such a scope later. A context
menu inside the scopes drowdown seems not to be a very clean UI.
(this seems somewhat related to the recent Mylar comments)