After closing Epiphany (being sure that the process has exited), any clipboard data I copied from Epiphany is lost. I found an older bug about this that is marked as fixed (bug #27411), so I assume this is a regression.
Ok, this might not be the same related issue, but anyway. Wayland clipboard support [0] doesn't allow clipboard content to be used after application quits. For X11, that issue was really fixed on [1], but removed in [0]. Bijiben uses webkit_web_view_execute_editing_command function to deal with clipboard, but it only keeps content after application quits on X11, not Wayland [2]. [0] https://bugs.webkit.org/show_bug.cgi?id=146574 [1] https://bugs.webkit.org/show_bug.cgi?id=27411 [2] https://bugzilla.gnome.org/show_bug.cgi?id=775312
I think it was broken again in X11 around the time Jim reported this bug. Anyway, yes, nowadays this is a mutter issue; to fix it, someone needs to add a clipboard manager protocol to either Wayland or xdg-shell, and implement it in mutter and GTK+. Nothing more to do here in WebKit. *** This bug has been marked as a duplicate of bug 180122 ***