I was thinking of creating a simple countdown (pomodoro) app. This would be an app that runs in the background after starting a countdown. In order to stay focused on my work, it would seem ideal to use a status icon to show the progress of the countdown. Otherwise, I’d have to flip back and forth between windows to check how much time is remaining. Once the countdown is done, then a notification would appear.
Is there an alternative to status icon that could be used for this? Or perhaps a different way to think about the problem?
MessageTray is still there, you would create a new source like that to display notifications in the normal way along with other notifications. You could also add static entry to the CalendarMessageList similar to the mpris section.
For something on the panel with arbitrary widgets, you would have to add another PanelMenuButton.