Closing the lid (clamshell mode) switches the MacBook screen off, but needs the lid shut, power and an external keyboard. If you want the lid open with only the big monitor on, Casement can turn the MacBook display off from its menu-bar panel, keeps one display on at all times, and turns everything back on with ⌃⌥⌘D.
Clamshell mode
With power, an external display and an external keyboard or mouse connected, shutting the lid keeps the Mac awake on the external display. The built-in screen and keyboard are then out of reach.
Lid open, screen off
Sometimes you want the built-in keyboard and trackpad but not the built-in panel. Casement switches that display off without unplugging anything, and windows move to the screens still on.
Safety
- One display always stays on.
- ⌃⌥⌘D lights every display again.
- A confirmation appears, and displays come back by themselves if you do not confirm.
Which setup suits you
| Setup | Built-in screen | Built-in keyboard |
|---|---|---|
| Clamshell (lid closed) | Off | Not reachable |
| Lid open, display off with Casement | Off | Usable |
| Mirror | Same picture on both | Usable |
Getting everything back
If you cannot see any display, press ⌃⌥⌘D. Casement keeps at least one display lit and brings the others back after its timeout if you do not confirm a change.
Questions people ask
Will this damage the display?
No. It uses the same switch-off the system uses for sleeping a display.
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..