How to show only one window on a projector from a Mac
What macOS does on its own
Open System Settings ▸ Displays, click the projector and look at Use as:
| Setting | What the audience sees | The catch |
|---|---|---|
| Mirror for Built-in Display | Your whole screen | Mail, chat, notifications and every window you open |
| Extended display | Whatever you drag onto it | One wrong drag and a private window is on the wall |
Extended mode comes closest: drag the slides over, keep everything else on the laptop. It still shows the desktop wallpaper and any window that lands there, and it can come up mirrored the next time you plug in.
Since macOS 15.2, mirroring to an AirPlay display such as a TV can share a single window or app, and some setups offer the same choice over a cable. See the FAQ below for how that compares.
Show one window with Stagemark
- Open the window you want to show, such as your slides or a browser window.
- Press ⌃⌥⌘A. Stagemark adds it to the picked windows. You can also open the Stagemark menu in the menu bar and choose Pick windows.
- Plug in the projector. The new screen turns black at once, and Stagemark asks what to do with it. Choose Start output.
- Only the picked window appears on the projector, at its own aspect ratio. Everything else stays on your laptop.
If the projector was already plugged in, press ⌃⌥⌘P to start and stop output.
While you present
- Switch windows: pick several windows, then use ⌃⌥⌘] and ⌃⌥⌘[ to step through them.
- Freeze: ⌃⌥⌘F holds the current picture while you type a password or look something up.
- Black screen: ⌃⌥⌘B blacks out only the projector.
- Keep working: click and type in the original window on your laptop. The projector only shows it.
Before your first talk
Stagemark needs Screen Recording permission to draw the window on the projector. macOS asks the first time you start output. Grant it ahead of time, because macOS may ask you to relaunch the app after turning it on. On macOS 15 and later, macOS asks about once a month whether to keep allowing it.
FAQ
Can I show just one app instead of one window?
Stagemark shows one window at a time. Pick each window of the app you need and switch between them with ⌃⌥⌘].
What happens if I drag another window onto the projector?
It goes under the black cover and the audience doesn't see it. If Accessibility permission is on, Stagemark also moves windows off the projector when output starts, so nothing sits hidden there.
Does this work with Keynote presenter view?
Presenter view uses both screens by itself. To use Stagemark, play the slideshow in a window on your laptop and pick that window instead.