Window Strip

The strip lines your windows up side by side, full height, never on top of each other, on a row that can be wider than your screen. The strip slides so the window you're in is always in view; the rest wait at the edges.

Turn it on

Open Settings → Window Strip and turn on Window Strip. It's off to start.
The windows on your screen slide into a row, each one a column.
Move through it with ⌃⌥← and →.

Each Space has a strip of its own. A window that's off the screen is parked as a thin sliver at the screen's edge, ready to slide back in.

Accessibility. The strip moves other apps' windows, so it needs the Accessibility permission, like Window management.

⌃⌥→ moves along the strip, and ⌃⌥1 jumps back to the first window.

Mac Setup

A few macOS settings fight the strip. The Mac Setup section of Settings → Window Strip checks each one and comes first while anything needs changing. ↵ on a row opens the System Settings pane that changes it.

Check	What the strip needs
Stage Manager	Off, or Stage Manager moves windows aside.
macOS tiling	Off, or edge dragging, the menu bar's fill and ⌥-drag tile windows on their own. `↵` here turns it off for you, and `↵` again puts it back.
Dragging to the top opens Mission Control	Off, or dragging a window up opens Mission Control.
Displays have separate Spaces	On, with more than one display, so each display has its own strip.
Automatically rearrange Spaces	Off, or macOS reorders your Spaces, and their strips with them.
Other window managers	Quit while the strip is on: two window managers would move the same windows.

Keys

Every strip key starts with the key prefix, ⌃⌥ to start. The keys work only while the strip is on, so the same keys can do something else when it's off.

Keys	What they do
`⌃⌥←` `→`	Focus the window on the left or right.
`⌃⌥⇧←` `→`	Move the window left or right along the strip.
`⌃⌥1`–`9`	Go to window 1 to 9.
`⌃⌥R`	Next Width.
`⌃⌥↩`	Full Width, and back.
`⌃⌥=` `−`	Wider and Narrower.
`⌃⌥C`	Center in the Strip.
`⌃⌥↑` `↓`	Focus the window above or below in a stack, or the previous or next tab.
`⌃⌥⇧↑` `↓`	Move the window up or down its stack.
`⌃⌥[` `]`	Stack into the column on the left or right.
`⌃⌥⇧[` `]`	Pop out of the stack to the left or right.
`⌃⌥⇧=` `−`	Taller or shorter in the stack.
`⌃⌥0`	Even heights in the stack.
`⌃⌥⇧T`	Show the stack as tabs, or split again.

Key prefix can be ⌃⌥, ⌥, ⌘⌥ or Hyper (⌃⌥⇧⌘). Changing it moves every strip key still on the old prefix; keys you changed keep theirs. With ⌥ alone, text fields lose ⌥← and ⌥→ while the strip is on. Hyper already holds ⇧, so the ⇧ keys have no key of their own there.
H J K L work as arrows (off to start): the prefix with H or L moves through the strip like ← and →, and J and K like ↓ and ↑.
Pause or Resume the Window Strip has no key until you give it one.
Edit Each Key opens the Window Strip section of Hotkeys, where any of them can change. See Hotkeys and aliases.

The indicator

A glass pill of the columns' app icons shows at the bottom of the screen, the window you're in marked and the ones on screen brighter. It fades after a second. Click an icon to go to that window; the pill never takes the keyboard from the app you're in.

Show the strip indicator chooses when: On each strip key (to start), While the key prefix is held, or Never.

A click on an icon slides the strip to that window; ⌃⌥5 goes to the fifth.

Column widths

Next Width steps through the width presets that are on: ½, ⅔ and full to start. The Widths section turns each of 25, 33, 50, 66, 75, 90 and 100 % on or off; at least one stays on.
Full Width gives the column the whole screen; press it again to go back.
Wider and Narrower change the width by a tenth of the screen.
Center in the Strip slides the strip so the column is in the middle of the screen.
If an app refuses a width, the column takes the width the window kept.

Wider and narrower, two width presets, centre, then full width and back.

Stacks and tabs

A column can hold up to three windows, one above the other. Stack into the column on the left (⌃⌥[) puts the window you're in under that column's; Pop out takes it back to a column of its own. Heights can change with the keys or by dragging a window's edge.

⌃⌥⇧T shows a stack as tabs: one window at a time, full height, under a glass tab bar with each window's icon and title. Click a tab, or use ⌃⌥↑ ↓, to show another.

Messages stacked under Notes, then the stack shown as tabs and split again.

New windows

New windows open Right after yours (to start), At the end or At the start.
New window width: Its own (the width it opened at, to start), ½, ⅔ or Full.
Background apps' windows don't take focus (on): a window from an app you're not in joins the strip without the strip sliding to it.
Float dialogs, panels and fixed-size windows (on): they stay where they open, above the strip.
Native tabs share one column (on): an app's own tabs, as in Finder or Terminal, move together.
When a window closes, minimizes, or its app hides or quits, the strip closes up. A hidden app's windows come back to their places when it shows again.

Layout and motion

Gap between windows (a slider, 0 to 32 pt, 8 to start): space between columns and at the screen's edges.
Stop above the Dock (on): columns end above the Dock, or beside it when it's on the side.
Slide windows (on): windows ease into place in a quarter of a second, at your display's refresh rate. Off, or with Reduce Motion, they land at once.
Centre the window you move to: Never (slide only as far as needed, to start), When the strip overflows the screen, or Always.

App rules

The App Rules section says how the strip treats an app: Tile (a column like any other), Float (above the strip, where it opens) or Leave Alone. Add App Rule… picks an app, which starts as Float; ↵ on its row steps through the three and ⌘⌫ removes it. Some apps float by default, like System Settings, Calculator, Passwords, Keychain Access and password managers; add a rule to change one.

Pause, quit and restore

Pause the Strip leaves every window where it is, moving any parked one fully onto the screen. Resume takes them back into their places.
When turned off, windows Go back to where they were before the strip (to start), or Stay where they are, moved fully on screen.
Saiki writes down where each window was before it moves it, so quitting Saiki, or opening it after a crash, puts every window back too.
Bring the strip back after a restart (on): the strip's order, widths, stacks and tabs are saved, and after Saiki or the Mac restarts, windows go back into their places.

Settings

Settings → Window Strip has the switch and every setting above, in the sections Mac Setup, Layout, New Windows, Moving Through the Strip, Keys, Widths, Indicator, Pause, Quit and Restore, and App Rules. Turned off, nothing of the strip runs.