Split screen on a Mac display: the layouts worth keeping

Searching for a way to split the screen on a Mac display usually ends in one of two places. Either the green button gets clicked, both apps go full screen, the menu bar disappears, and the arrangement turns out to be harder to leave than it was to enter. Or two windows get dragged into rough halves by hand, only for the next app launch to cover them both. These are not the same problem, because macOS has two separate features that both get called split screen, and they behave differently on purpose.

The distinction matters more on a large or external display than it does on a laptop. What follows is what each feature actually locks, which one survives an app switch, the setting that quietly blocks split layouts on a second monitor, and where the arrangement tends to fall apart once most of the work lives inside a browser.

Two features, one name

The older of the two is Split View. It takes two apps, puts them side by side, and moves the pair into a new desktop space of their own. Apple's documentation is explicit about that last part: the Split View is created in a new desktop space. That single sentence explains most of the frustration people report. The two apps are no longer on the desktop. They live somewhere else, reachable through Mission Control or a three finger swipe, which is why a third app launched afterwards appears to have replaced them.

The newer feature is window tiling. A window gets dragged to an edge or a corner of the screen, or a layout gets picked from a menu, and the window snaps to fill that region. Nothing goes full screen. Nothing moves to a new space. Apple's description of the tiling behavior states plainly that when a window is moved to one side of the screen this way, the menu bar and Dock remain visible. The windows stay ordinary windows.

Both features are reached from the same green button in the top left corner of a window, which is the main reason they get confused. Holding the pointer over that button shows a menu with several groups in it. The layouts under Move and Resize tile the active window. The layouts under Fill and Arrange tile more than one window at once. Full Screen is a separate submenu, and choosing Left of Screen or Right of Screen from it is what starts Split View rather than tiling.

Knowing which of the two is running answers the question that usually follows. If the menu bar and Dock are visible, the windows are tiled and can be moved, resized, or covered like any other window. If the menu bar has gone and a swipe is needed to get back to the desktop, the apps are in Split View and are pinned into their own space until that space is exited.

What Split View actually locks

Split View is worth using deliberately, not by accident. It removes the menu bar, the Dock, and every other window from view, and that is the entire point. For a pass of focused work with a document on one side and a reference on the other, nothing else in macOS gets as close to a two panel application.

Entering it takes two steps. On the first app, hold the pointer over the green button, then choose Full Screen followed by Left of Screen or Right of Screen. The other half of the screen then shows the remaining windows, and clicking one puts it in the empty side. From that point the pair behaves as a unit.

Inside Split View, a handful of adjustments are available and most people never find them. The divider in the middle can be dragged left or right to change the proportions, and double clicking it returns both sides to equal width. A window can be moved to the other side by dragging it with its title and toolbar. Either side can be swapped for a different app through the green button and the Replace Tiled Window option. Either side can also be released, through Move Window to Desktop for a normal window or Make Window Full Screen for a full screen one. In both cases the app left behind becomes full screen in its own space, which is worth knowing before clicking.

The menu bar and Dock are not gone permanently. Moving the pointer to the top of the screen brings the menu bar back, and moving it toward the Dock's position brings that back too. The faster exit is Mission Control, reached with Control and the Up Arrow key or a three or four finger swipe upward. Holding the pointer over the Split View thumbnail in the Spaces bar reveals an Exit button that ends the arrangement.

The hard limit is that Split View holds exactly two apps. There is no three panel version. On a 27 inch or larger display, splitting into two halves wastes most of the width, which is the reason the newer tiling feature exists.

Window tiling, and the settings that control it

Tiling is the feature that fits a large display, and it has four separate entry points.

Dragging is the fastest. A window dragged to the left or right edge, to a corner, or up to the menu bar snaps into the highlighted area when released. The corner targets give quarters, and the menu bar target fills the desktop. One caveat is documented by Apple: dragging a window all the way through the top edge opens Mission Control instead, and the way to stop that is to turn off the option to drag windows to the top of screen to enter Mission Control in Desktop and Dock settings.

Holding the Option key while dragging is the second route, and it reaches the top edge as well as the left, right, and corners. The third is the green button, with layouts grouped under Move and Resize for the active window and under Fill and Arrange for several windows at once. Pressing Option while that menu is open reveals additional layouts, including a Center option and a Fill option for the desktop. The fourth route is the Window menu in the menu bar, where Move and Resize contains layouts grouped under Halves, Quarters, and Arrange.

Four toggles govern the behavior, and they sit together in System Settings under Desktop and Dock, in the Windows section. They are the option to drag windows to the left or right edge of screen to tile, the option to drag windows to the menu bar to fill screen, the option to hold the Option key while dragging windows to tile, and the option for tiled windows to have margins. That last one is the setting to change if tiled windows appear to leave gaps between them for no reason.

Two keyboard shortcuts are worth committing to memory alongside these. Fn with Control and F fills the desktop with the active window, and Option clicking the green button again returns it to its previous size. Option with Command and W closes every window belonging to the current app, which is the quickest way to clear a display that has filled up.

Which layout fits which display

The right choice depends on the width of the display and on whether the arrangement needs to survive an app switch.

Layout	Menu bar and Dock	Number of apps	Survives launching a third app	Best on
Split View	Hidden	Exactly two	Yes, because the pair has its own space	Laptop display, focused writing
Tiled halves or quarters	Visible	Two to four	No, a new window can cover them	27 inch and larger, external display
Full screen	Hidden	One	Yes, own space	Video, single long document
Manual positioning	Visible	Any	No	Irregular window sizes

The pattern behind the table is simple. Anything that hides the menu bar has been moved into its own space and is therefore protected from new windows. Anything that keeps the menu bar visible is still on the desktop and can be covered at any moment. Neither is better. They answer different questions.

For a display wide enough to hold three or four readable windows, tiling is the only option that uses the space, since Split View caps at two. For a laptop screen where two windows is already the practical maximum, Split View gives more usable pixels because the menu bar and Dock are out of the way.

External displays and the setting that blocks split layouts

Split View on a second monitor fails for one reason more often than any other, and it is a single checkbox. Apple's guidance is direct: to use apps in Split View on other displays, the option for displays to have separate Spaces has to be turned on in Desktop and Dock settings. With it off, each app that goes full screen takes over the main display and leaves the other one showing a blank desktop picture, which looks like a bug and is not one.

Spaces themselves are the other half of a multi display arrangement, and they are generous. Up to 16 spaces can be created, each holding its own set of windows and its own wallpaper. Moving between them takes Control with the Right or Left arrow key, or a three or four finger swipe.

The setting that pays for itself on a multi display desk is assignment. Control clicking an app's icon in the Dock, then choosing Options, gives a list under Assign To with four values: All Desktops, This Desktop, Desktop on a numbered display, and None. Assigning the chat tool to one display and the editor to another means each app opens where it belongs every time, with no dragging. This is the only part of a split layout that macOS remembers for you across restarts.

One related default catches people out. When switching to an app, macOS jumps to a space that already has windows open for that app. A new document can therefore appear in a space that was left hours ago. The toggle is in Desktop and Dock settings under Mission Control, described as switching to a Space with open windows for the application.

Where the layout falls apart

A split layout built out of applications tends to hold. A split layout built out of browser tabs does not, and that is now the more common case.

The reason is that tiling and Split View operate on windows. A browser holding a mail client, a chat tool, a task tracker, and two documents is one window as far as macOS is concerned. Tiling it to the left half tiles all of it. Getting the mail on the left and the chat on the right means pulling tabs out into separate windows first, and those windows carry no identity of their own. Two accounts on the same service produce two windows with near identical titles, so the Command and Tab list stops being useful and the arrangement has to be rebuilt by eye every morning.

This is the point at which the layout problem turns into a window management problem. Keeping each web app in a window that persists, with its own session, makes the split layout stable, because the windows being tiled are stable. A tool that keeps each web app in its own window handles that, and the way sets of those windows get saved and reopened together is worth reading about on the Workspaces page. The scope of what can live in such a window, including two accounts of the same service signed in at once, is set out under Features, and whether a given service is covered is listed under Supported apps. For anyone weighing this against the established options, the side by side breakdowns at Compared with Wavebox and Compared with Shift name the differences in price and platform without dressing them up.

What to change first

Open System Settings, go to Desktop and Dock, and in the Windows section decide the four tiling toggles deliberately rather than leaving them at their defaults. If a second display is connected, turn on the option for displays to have separate Spaces, then assign the two or three apps used all day to specific displays through the Dock. If the windows being arranged are mostly browser tabs, the layout will keep collapsing until each web app has a window of its own, which is the problem SpaceDeck is built to solve.