Menu bar extra

Every desktop keeps a strip of the screen for the system itself, and lets applications rent a slot in it. On one platform that strip is the right end of the menu bar and the slot is called a status item; on another it is the notification area at the end of the taskbar and the slot is called a tray icon. The component is the same either way: a small, always-present handle for an application that is mostly not on screen, showing a glanceable state in its icon and opening a compact panel of status and controls when clicked.

It is the right home for exactly one kind of software, the sort that runs continuously and is only occasionally worth looking at. A backup agent, a VPN, a clipboard manager, a time tracker, a music player. What all of those share is that their main window is a chore, and that their state (connected, syncing, recording, paused) is worth reading without opening anything. Everything else that ends up in the tray is there because the developer did not want to be closed, which is why platform guidelines have spent two decades telling people not to put an icon there, and why users have spent the same two decades hiding them.

The confusion worth clearing up is with the notification centre. A notification centre is a place, owned by the system, where messages from every application collect and wait to be read. A menu bar extra is a handle, owned by one application, that is present whether or not it has anything to say. They sit in the same corner of the screen and they answer different questions: what happened while I was away, versus what is this program doing right now. The neighbours in the strip are the system’s own status items and, at the other end of the window, the title bar and its window controls. Note also that a status bar is the application’s own strip inside its own window, whereas this one lives outside every window in a bar the application does not own.

Design it as if it will be looked at for half a second, because it will. The icon carries the state, so it needs a shape that reads at sixteen pixels in a monochrome template (colour is often stripped by the system), and it needs to sit still: an icon that animates in the corner of every screen is an interruption the user never asked for. The panel it opens is a popover with a job, not a menu of everything: current status, the one or two actions worth taking from here, and a way into the real application. Give it an explicit dismissal (choose something, press Escape, click away) rather than making the icon a toggle, and remember that on most systems the user can drag the item out of the bar entirely, so nothing may be reachable only from here.