Arrange the displays in macOS
- Connect the external display and open System Settings > Displays.
- Choose whether to extend or mirror the desktop, then arrange the on-screen rectangles to match the physical placement.
- If available, choose which display is the main display and record where macOS places the menu bar.
- Open Mission Control on each display to see which Spaces belong to that screen.
Apple’s Displays settings guide describes Arrange, mirroring, extending, and main-display selection. Its available controls depend on the hardware.
Check NotchDock on one layout
The reviewed source initializes its panel around NSScreen.main. It does not document a user-facing “follow active mouse screen,” “anchor to main display,” or “dual-screen mirroring” preference. Open the app with the layout set, note which screen receives the panel, then switch the main display or disconnect the monitor once and note the change.
Keep a useful support record
Write down Mac and monitor models, cable/dock, macOS and NotchDock versions, mirror/extend mode, main display, Space settings, and the result after reconnecting. Avoid calling the setup supported just because one arrangement worked. This page does not claim automatic topology switching, clamshell behavior, or support for every portrait display.