Open Casement's control panel from the menu bar, find Displays, choose the display to switch off and confirm. Windows move to the screens that remain on. One display always stays on, ⌃⌥⌘D turns every display back on, and Casement restores the screen by itself if you do not confirm.
Before you start
You need Casement installed. This feature switches a display off rather than disconnecting it, so the cable stays in and the screen wakes instantly.
It is designed so you cannot lose every screen: one display always stays on.
Steps
- Connect your external monitor and check that it shows your desktop.
- Open Casement's control panel from the menu bar and find the Displays section.
- Choose the display to switch off, such as the MacBook's own screen. If it is the only one on, Casement will not let you.
- Confirm. Windows move to the screens still lit, and a countdown starts for the confirmation.
- Confirm again within the countdown if everything looks right.
- To bring the screen back, press ⌃⌥⌘D or choose it again in the panel.
Check that it worked
The MacBook screen should be dark and the windows should now be on the monitor.
Press ⌃⌥⌘D to confirm the screen returns.
If something goes wrong
- A screen stays dark. Press ⌃⌥⌘D. If that does not help, unplug and replug the display or sleep and wake the Mac.
- Windows are hard to find. Use the window switcher or Mission Control.
- The Mac sleeps with the lid closed. Closed-lid behaviour is a macOS matter; see the guide.
What to do next
See turn off a display and use an external monitor and switch off the MacBook screen.
Why people do this
- The laptop sits on a stand and its screen is below eye level, so it is a distraction.
- The lid is open for better cooling or to use the built-in camera, but the display is not needed.
- A shared TV or projector should be blank until needed.
- Reducing light and glare on a desk used for long sessions.
Because the display is switched off and not unplugged, there is no cable shuffling and the screen returns instantly when you want it.
A safe routine
Before switching a display off, check that the one staying on shows your windows. After confirming, test the shortcut that restores everything, ⌃⌥⌘D, once so you know it works. If you present with an external display, switch the built-in one off before the meeting so you can see your notes on the screen that stays on, not on the one the audience sees.
Questions people ask
Does it disconnect the display?
No. It switches the display off while it stays connected.
Can I lose all my screens?
No. One display always stays on, and Casement restores displays if you do not confirm.
Try Casement
Casement is a menu-bar app for Mac that puts each Chrome profile in the Dock as its own icon and adds snap layouts, hover-to-focus, a window switcher, Dock window lists, a drop shelf and display controls..