Diagnostic messages should be copyable from the window

E.g. "No traffic can be observed because the adapter you selected has no active addresses" should be easy to copy and paste to a bug report.

Alternatively, some of the messages displayed in GUI can be duplicated to stderr.

No files, tests, or entry points are named. Start by locating where GUI diagnostic messages are rendered, then determine whether the issue should support copying from the window or duplicate messages to stderr; done means the chosen approach makes the example message usable in a bug report.

Written by the indexing model from the issue text.