When you receive a message from another device, and your chat window is in the background, Underpass will show a notification. Underpass supports banners, alerts, sounds, and Dock icon badges. You can configure Underpass notifications in System Preferences.
If Underpass is the active application, and a chat window is frontmost, then Underpass will not show notifications for new messages in that chat.
If you click on a banner or alert, Underpass will bring the relevant chat window to the front so you can see it.
The Underpass icon in the Dock keeps a count of the number of new, unread messages.
If you bring a chat window to the front of the screen, Underpass removes the new messages in that window from the count. Once you've seen all of the chat windows with new messages, the badge on the Dock icon disappears.
It is important to consider whether you want to show notifications on the lock screen. Banners and alerts may contain sensitive information, so if you're worried about someone reading them while you are away from your Mac, you'll want to turn off this preference.
In addition to showing a notification, Underpass will also bounce its Dock icon once when you receive a new message from a chat in a background window. This feature is for users who choose to hide their Dock and thus won't see the counter in the Dock icon badge.