RibbonSplit View not working on a Mac: the fixes
The most common cause is a setting: Split View needs Displays have separate Spaces turned on, in System Settings → Desktop & Dock, even on a Mac with one screen. If that's on, the app itself may not support Split View, or its window can't be resized. Here's how to check each, and what to use when Split View won't do.
How Split View is supposed to work
- Hover over the green button at the top left of a window.
- Choose the full-screen option for the left or right of the screen. On macOS 15 Sequoia and later it's under Full Screen; older versions say Tile Window to Left of Screen and Tile Window to Right of Screen.
- The other half shows thumbnails of your other windows. Click one to fill it.
Both windows then share a full-screen Space. Drag the divider to change the split.
1. Turn on "Displays have separate Spaces"
System Settings → Desktop & Dock → scroll to Mission Control → Displays have separate Spaces. Turn it on, then log out and back in; the change doesn't apply until you do. This setting matters even if you've never plugged in a second display.
2. Check the app supports it
Not every app can go into Split View. Some games, some older apps, and apps with fixed-size windows don't offer the option. If the full-screen tile options are missing or greyed out for one app but work for others, it's the app.
3. The second window doesn't appear
The empty half only shows windows that can join Split View. If the one you want is missing:
- It's minimized or its app is hidden. Restore it first, then start again.
- It's already full screen in its own Space. Leave full screen first (⌃⌘F).
- The app doesn't support Split View (see above).
4. Try it from Mission Control
Make one app full screen, then open Mission Control (⌃↑) and drag another window onto that full-screen app's thumbnail in the bar at the top. The two pair up into Split View.
5. Restart the Dock or the Mac
Mission Control and Spaces are run by the Dock process. If everything above checks out and Split View still won't start, restart the Mac, or run killall Dock in Terminal. The Dock relaunches straight away.
Often, you don't need Split View
Split View has hard limits: exactly two windows, in a separate full-screen Space, with the menu bar and Dock hidden. Switch to a third app and you leave the pair behind.
- macOS 15 and later can tile two windows side by side on your normal desktop: Fn⌃← and Fn⌃→, with no separate Space. See how to tile windows on a Mac.
- Three windows? See split the screen into three.
- More windows than fit? A scrolling window manager puts every window side by side on a strip that scrolls. In Ribbon, a third or fourth app adds a column instead of breaking the pair, and the strip follows your swipe. Try it in the live demo; it's $9.99 once.
FAQ
Why can't I use Split View on my Mac?
Usually because "Displays have separate Spaces" is off. Turn it on in System Settings → Desktop & Dock and log out. Otherwise the app doesn't support Split View.
Why is the Split View option missing from the green button?
On macOS 15 and later the left and right full-screen options sit under Full Screen in the green button's menu. If they're missing for one app only, that app doesn't support Split View.
Can I split screen without full screen?
Yes, on macOS 15 and later: Fn⌃← and Fn⌃→ tile windows on your normal desktop.