The yellow balloon, for everything. Notifications from every program now appear as the classic balloon over the notification area: yellow, rounded, black-bordered, with the icon, a bold title, the text, a close box and a tail pointing at the tray. The desktop provides the org.freedesktop.Notifications service itself, so Firefox, mail clients, music players, notify-send and anything using libnotify all show it, queued one after another. Clicking the balloon is the notification's action; the close box dismisses it. A notification daemon already running in the session (dunst, xfce4-notifyd) is asked to step aside.
Also: w2kwm --restart now execs the binary on disk rather than the image it was started from, so a restart after a rebuild really runs the new build. Sessions started before this release need one more log off and on to pick that up; after that the update command handles it.
curl -sL jacktulli.github.io/w2k | sh