Mac Split View: keeping two web apps in sight at once

Two apps need to be visible at the same time. One holds the thing being written, the other holds the thing being read. macOS offers at least three different answers to that, they behave nothing alike, and the one most guides describe first is the one that suits the fewest people. Split View is a real feature with a real purpose, but it is not a window layout. It is a place.

Getting the distinction right decides whether the arrangement survives the rest of the working day or falls apart the first time a notification arrives.

What Split View actually does

Hold the pointer over the green button in the top-left corner of a window, then choose Full Screen, then Left of Screen or Right of Screen. The window expands to fill that half. The other half shows the remaining windows, and clicking one puts it opposite the first.

The important part is what happens next. Apple's own description is explicit: the Split View is created in a new desktop space. The pair is no longer on the desktop. It has moved somewhere else, and that somewhere else contains only those two apps.

That single fact explains almost every complaint about Split View.

The menu bar hides until the pointer reaches the top of the screen. The Dock hides until the pointer reaches wherever the Dock lives. Window titles and toolbars hide until the pointer moves up. Nothing else can be placed beside the pair, because the space holds two apps and no more. Switching to any third app leaves the space entirely, and coming back means returning to it through Mission Control with Control-Up Arrow, or by swiping across with three or four fingers.

For a genuinely two-app task with no interruptions, that isolation is the feature. A translation window beside a source document, a spreadsheet beside a form. For a working day that involves a chat app, a mail app and a calendar, the isolation is the problem.

Tiled halves are a different feature with a similar picture

Since macOS Sequoia 15, the same green button carries a second set of options under Move & Resize, and those are not Split View. Choosing the left or right half there fills half the desktop while the menu bar and Dock stay visible. Nothing moves to a new space. The window is still a window, still on the desktop, and a third app can be dragged on top of it.

Those layouts have keyboard shortcuts, which the Split View options do not:

Action	Shortcut	Result
Left	Fn-Control-Left Arrow	Active window fills the left half of the desktop
Right	Fn-Control-Right Arrow	Active window fills the right half of the desktop
Left and Right	Fn-Control-Shift-Left Arrow	Active window left, second window right
Right and Left	Fn-Control-Shift-Right Arrow	Active window right, second window left
Fill	Fn-Control-F	Active window fills the desktop
Return to Previous Size	Fn-Control-R	Untiled, back to the size it had before

The pair shortcut is the one worth memorising. Fn-Control-Shift-Left Arrow arranges two windows in one keystroke, which is the outcome most people are after when they search for Split View in the first place.

Window tiling arrived in macOS Sequoia 15. On macOS Sonoma 14 and earlier none of it exists, which is why a good deal of published advice sends people to Split View as though it were the only option. Dragging a window to a screen edge, a corner or the menu bar also tiles it on Sequoia and later, and holding Option while dragging snaps it faster.

Three routes to the same layouts

The green button is not the only way in. The Window menu in the menu bar carries the same options: Move and Resize holds the Halves and Quarters layouts plus the Arrange sets for multiple windows, Center and Fill sit alongside them, and Full Screen Tile holds the Split View pair. Holding the Option key while the green button menu is open reveals additional layouts that are hidden by default.

Two settings are worth knowing before any of this is blamed for misbehaving. Edge dragging and Option dragging can each be turned off in window tiling settings, so a Mac where dragging to an edge does nothing may simply have the feature disabled. Separately, dragging a window all the way through the top edge of the screen opens Mission Control rather than filling the desktop, and that behaviour is its own switch in Desktop and Dock settings.

Which of the three to use

Approach	Menu bar and Dock	Lives in	Room for a third app	Keyboard shortcut
Split View	Hidden until the pointer moves	A new space of its own	No	None for entering it
Tiled halves	Visible	The current desktop	Yes	Fn-Control-Left or Right Arrow
Two ordinary windows, aligned	Visible	The current desktop	Yes	None, but they snap as they meet

The third row is underrated. Dragging one window close to another aligns it without overlapping, and dragging the shared edge resizes both to match. That produces the same picture as tiled halves with arbitrary proportions rather than a fixed fifty-fifty split, which matters when one of the two apps has a sidebar that needs a certain width.

Split View is the right choice when the two apps are the whole task. Tiled halves are the right choice when the two apps are part of a larger day.

The problem when both apps are web apps

Here the question changes shape. Two native apps are two windows, and any of the three approaches above will place them. Two web apps in the same browser are two tabs in one window, and no layout feature can put two tabs side by side. A layout arranges windows. It has no opinion about what is inside them.

The usual workaround is to open a second browser window and drag one tab into it. That works for two unrelated services. It stops working the moment the two tabs are the same service signed in to two accounts, because both windows share one session, and signing in to the second account signs out of the first. Two browser windows, one cookie jar.

It also degrades over a day. Browser windows accumulate tabs. The window that was opened to hold the calendar now holds the calendar plus nine other things, and which one is showing is no longer predictable. A layout that depends on a specific tab being in front is not a layout.

A tool built around this problem gives each service its own window and its own session container instead of a tab, so that the left half of the screen stays the same service all day. An app aggregation browser for macOS treats each web app as a separate place rather than a page, and the workspaces model is what makes two accounts in the same service coexist without either signing the other out. Whether that helps depends on which services are involved, so the supported apps list is the page to check first.

Spaces are the same idea with more room

Since a Split View is a space, it helps to know what else spaces can do, because the pair is often not the real requirement. The real requirement is that a particular set of apps stays arranged and stays reachable.

Additional desktop spaces are created in Mission Control and switched with Control-Left Arrow and Control-Right Arrow. A full screen app occupies a space of its own, and so does each Split View. That means a working day can be laid out as places rather than as a pile: the main task on the desktop, a two-app pair in the next space along, a reference app full screen in the one after.

Mission Control is also the fastest way to build a Split View out of something already full screen. Press Control-Up Arrow, drag a window from Mission Control onto the thumbnail of the full screen app in the Spaces bar, then click the Split View thumbnail that appears. Dragging one app thumbnail onto another in the Spaces bar does the same thing. This route avoids the green button entirely, and it is the only comfortable way to add a second app to something that is already full screen.

The limit is switching cost. Every jump between spaces is an animation and a moment of reorientation, and the more spaces exist the harder it becomes to remember which one holds what. Spaces reward a small fixed number of places with stable contents. They punish improvisation.

Adjusting a Split View without losing it

Once a Split View exists, several adjustments are available from inside it, and all of them are easy to trigger by accident.

Dragging the separator bar in the middle moves the boundary. Double-clicking the separator bar returns both sides to equal width, which is the fastest fix after a stray drag. Dragging a window by its title and toolbar to the other side swaps the two apps left for right.

To change one of the apps, click that window, hold the pointer over the green button, choose Replace Tiled Window, then click the window to use instead. Clicking the desktop instead cancels the replacement.

Two menu items end the arrangement, and the result of both surprises people. Move Window to Desktop sends the chosen app back to the desktop. Make Window Full Screen sends it to full screen on its own. In either case the app left behind does not return to the desktop with it. It becomes full screen in its own space, and reaching it again means Control-Up Arrow into Mission Control and a click in the Spaces bar. Split View is exited one window at a time.

External displays and apps that refuse

Two recurring failures have nothing to do with technique.

The first is an external monitor. Whether each display keeps its own spaces is a setting, and it governs how Split View behaves across two screens. Apple's instruction is to make sure the option for displays to have separate spaces is turned on in Desktop and Dock settings. With it off, a full screen or Split View arrangement takes over both displays at once, which accounts for most of the reports that Split View has ruined a dual monitor setup.

The second is an app that will not cooperate. Apple's wording is that many apps support Split View, not all. Some windows cannot be moved at all. Others have a minimum width that makes half of a laptop display unusable, so the app technically enters Split View and then shows a cramped, unusable column. Utility windows, preference panes and dialog boxes generally refuse outright. When the green button offers no Full Screen options for a window, that window is not a candidate, and no setting changes it.

What to change first

Try Fn-Control-Shift-Left Arrow on the two windows that need to be visible together, and keep Fn-Control-R for undoing it. That covers the ordinary case without entering a separate space at all. If the two things that need to be side by side are both web apps living as tabs in one browser, the layout is not the problem, and a browser that gives each service its own window and session, such as SpaceDeck, is the piece to test instead.