How to split the screen on a Mac and keep two apps in view

Two apps need to be on screen at once. A spreadsheet and the document quoting from it, a design tool and the ticket describing the change, a reference page and the thing being written. The Mac has more than one answer to that, and the answers behave differently enough that picking the wrong one causes the exact frustration that sends people searching. One of them hides the menu bar and creates a new space. One of them leaves the desktop alone. They are both reached from the same green button, which is why they get confused.

This lays out both, what each one changes, why the green button sometimes refuses, and where the two-app answer stops being the right answer at all.

Two features, one green button

Split View is the older feature. It puts two apps side by side in full screen, in a new desktop space of their own. Apple's guide describes it plainly: hold the pointer over the green button in the top-left corner of a window, choose Full Screen, then Left of Screen or Right of Screen. The window moves aside, the remaining windows appear on the other half, and clicking one of them fills the second half. The pair now lives in its own space. The menu bar hides until the pointer goes to the top of the screen. The Dock hides until the pointer goes to where it sits.

Window tiling is the newer one. It arrived with macOS Sequoia 15 and is not present in the Sonoma 14 version of the Mac user guide. Tiling snaps a window to half or a quarter of the desktop and stops there. No new space is created. The menu bar and the Dock stay visible. Other windows stay where they are. It is closer to what people coming from Windows expect.

The practical difference is what happens to everything else. Split View takes the two apps out of the desktop and puts them somewhere else, so the rest of the work is one Mission Control gesture away. Tiling leaves the two apps on the desktop with everything else behind them. Neither is better. They answer different questions.

Split View, exactly

Start with the window that should end up on one side.

1. Hold the pointer over the green button in the top-left corner. Do not click it.
2. In the menu that appears, hold the pointer over Full Screen, then choose Left of Screen or Right of Screen.
3. The other open windows appear as thumbnails on the remaining half. Click the one that should sit there.

Once the pair exists, a few controls matter more than the rest.

Resizing. Move the pointer over the separator bar in the middle and drag it left or right. Double-clicking the separator returns both sides to equal width. That double-click is the fastest way out of a layout that has drifted.

Swapping sides. Drag a window by its title and toolbar across to the other side.

Replacing one app without losing the pair. Click the window to be replaced, hold the pointer over its green button, choose Replace Tiled Window, then click the window that should take its place. Clicking the desktop cancels.

Getting out. Hold the pointer over the green button and choose Move Window to Desktop. That app returns to the desktop. The app left behind is now full screen in its own space, and it is reached by pressing Control and the Up Arrow, or swiping up with three or four fingers, to open Mission Control and clicking it in the Spaces bar. Choosing Make Window Full Screen instead of Move Window to Desktop has the same effect on the partner.

If an app is already full screen and a second app should join it, open Mission Control, drag a window from the Mission Control layer onto the thumbnail of the full-screen app in the Spaces bar, then click the Split View thumbnail that forms.

Tiling, and the settings that make it behave

Tiling has four entry points, and most people only ever learn one.

Drag to an edge. Drag a window to the left edge, the right edge, a corner, or the menu bar at the top. Release when the highlighted area appears. Dragging to the menu bar fills the desktop.

Option and drag. Hold the Option key while dragging toward an edge or corner. This snaps faster than waiting for the highlight.

The green button. Hold the pointer over it. Layouts under Move and Resize tile the active window. Layouts under Fill and Arrange tile several windows at once. Holding Option while the menu is open reveals additional layouts.

The Window menu. The same layouts sit under Window, then Move and Resize, grouped as Halves, Quarters and Arrange. Center and Fill are there too. This is the entry point worth knowing, because it is the one that shows the exact names of the layouts rather than icons.

One setting is worth changing on day one. Dragging a window all the way through the top edge of the screen opens Mission Control, which is rarely what was intended while trying to tile. That behaviour is switched off under System Settings, then Desktop and Dock, by turning off the option to drag windows to the top of the screen to enter Mission Control.

For keyboard people, pressing Fn, Control and F fills the desktop with the active window, and Option-clicking the green button afterwards returns it to its previous size.

Why the green button sometimes does nothing

Three causes cover almost every case.

The app does not support it. Apple's own wording is that many apps support Split View, not all. Anything with a fixed window size, a utility that draws its own window chrome, or an older app that never adopted the full screen API will refuse. Nothing in settings fixes this.

The window is already in a state that blocks it. A window that is minimised to the Dock, or one that belongs to an app currently in full screen, will not offer the option until it is restored.

Separate spaces are switched off. To use Split View on a display other than the main one, the option for displays to have separate spaces has to be on. It lives under System Settings, then Desktop and Dock, then Mission Control. The same switch is a prerequisite for Stage Manager, which is why turning one off can quietly break the other.

If the green button works but the layout snaps back, the usual cause is a minimum window width. A sidebar-heavy app on a 13 inch screen can refuse to shrink below a width that leaves the other half unusable. Collapsing the sidebar first often fixes it.

Which one to reach for

	Split View	Window tiling
Available since	Long before macOS Sequoia	macOS Sequoia 15
Creates a new space	Yes	No
Menu bar and Dock	Hidden until the pointer reaches them	Always visible
Number of apps	Two	Two, or four in quarters
Other windows	Left behind on the desktop	Still there, behind
Best for	One task that needs isolation	Quick side by side, then back

The honest rule is about duration. Split View suits work that will last an hour and needs the rest of the machine out of sight. Tiling suits work that will last five minutes. Setting up a Split View space to check one figure costs more than it returns, because leaving it means a Mission Control gesture rather than a click.

What changes with a second display

Adding a display does not simply double the available halves, because spaces and displays interact.

With the option for displays to have separate spaces switched on, each display keeps its own set of spaces and its own menu bar. A Split View pair created on the external display stays on that display, and swiping between spaces on one screen leaves the other screen untouched. This is the setup most people want with an external monitor, and it is also the setup Split View requires on a secondary display.

With that option switched off, the displays behave as one continuous desktop with a single menu bar. Full screen and Split View then take over both screens at once, which is almost never the intent. If Split View on an external monitor has ever produced a black second screen, this setting is the reason.

Tiling behaves more simply. A window tiles to the half or quarter of whichever display it is dragged to, and nothing about spaces is involved. On a wide external monitor, halves are often too wide to read comfortably, and the quarter layouts under Fill and Arrange usually produce a better result than the halves that seem like the obvious choice.

One more detail catches people with laptops. A Split View pair built at the internal display's dimensions does not re-lay-out when the Mac is later connected to a larger monitor. The pair keeps its proportions and the separator sits in the old place. Dragging the separator once, or double-clicking it to reset to equal halves, is the fix, and it has to be done again on disconnect. Saved layouts in a third party tool exist largely to remove this particular repetition.

Where two panes stop being enough

Split screen answers a question about two documents. It does not answer the question most people actually have, which is about six or seven web applications that each want a window.

A mail client, a calendar, two chat services, a project tracker, a customer record system and an AI assistant do not fit into halves and quarters. They fit into tabs, which is how most of them end up, and tabs are where the original problem returns. A tab strip with twenty entries gives no reliable way to tell which tab holds the message that just arrived, and the favicon of a service signed in to two different companies is identical in both.

That is a different shape of problem, and the tools built for it keep each web application in its own persistent container rather than in a shared tab strip. A browser built around workspaces rather than tabs holds each service in a fixed position, keeps separate logins for the same service apart, and makes switching a matter of clicking a known slot rather than scanning a row of icons. The supported apps list for tools in this category is worth reading before committing, because the value depends entirely on whether the specific services in daily use are covered.

Window management and app management are separate problems. Solving the first does nothing for the second, which is why people who have learned every tiling shortcut still lose messages.

What to change first

Turn off the option that opens Mission Control when a window is dragged to the top of the screen, then spend a day tiling with Option and drag instead of using the green button menu. If after that day the recurring annoyance is still about which web application a message arrived in rather than about window positions, the problem is not layout, and a tool like SpaceDeck that gives each service its own place is the thing to test next.