I hope that you enjoyed Saturday’s Mac Riddles, episode 173. Here are my solutions to them.
1: Vigilant window you have to dismiss.
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Alert
Vigilant (alert) window you have to dismiss (what you do with an Alert).
2: Symbolic flag slides past at the top right.
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Banner
Symbolic flag (banner) slides past at the top right (what a notification banner does).
3: Distinctive emblem appears docked in red.
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Badge
Distinctive emblem (badge) appears docked in red (shown as a red circle on the app’s icon in the Dock).
The common factor
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They’re all interface elements used by macOS Notifications.
I look forward to your putting alternative cases.