Make double-clicking a title bar zoom instead of minimize

If you've ever accidentally double-clicked a window's title bar and watched it vanish into the Dock, you're not alone. macOS defaults to minimizing on that gesture — but you can change it to zoom, fill, or do nothing at all. Here's how.

What the setting actually does

The macOS setting is called Double-click a window's title bar to: and it controls what happens whenever you double-click on the grey bar at the top of a standard macOS window. The options are:

• Minimize — the default; sends the window to the Dock.
• Zoom — resizes the window to its "ideal" size (the old behaviour of the green traffic-light button before full-screen was introduced).
• Fill — expands the window to fill the display without entering full-screen mode (available on macOS Sonoma and later).
• None — the double-click does nothing.

Most people who switch away from Minimize choose Zoom. It expands the window to a sensible size without hiding it in the Dock or taking over the full screen — you can still see other windows behind it and switch between them normally.

Method 1: System Settings

1. Open System Settings from the Apple menu.
2. Click Desktop & Dock in the sidebar.
3. Find the option labelled "Double-click a window's title bar to:"
4. Click the dropdown and select Zoom (or Fill, or None — your preference).

The change takes effect immediately. No restart needed — try it on the next window you open.

On macOS Ventura (13) and earlier, this setting lives in System Preferences → Dock & Menu Bar.

Method 2: Terminal command

Open Terminal (Applications → Utilities) and run one of the following:

# zoom to ideal size on double-click
defaults write -g AppleActionOnDoubleClick -string "Maximize"

# fill the screen (Sonoma+ only)
defaults write -g AppleActionOnDoubleClick -string "Fill"

# do nothing on double-click
defaults write -g AppleActionOnDoubleClick -string "None"

Note that the Terminal value is "Maximize" even though the System Settings label says "Zoom" — both refer to the same behaviour.

How to undo it

To restore the default (Minimize), run:

# restore default: minimize on double-click
defaults write -g AppleActionOnDoubleClick -string "Minimize"

Or simply go back to System Settings → Desktop & Dock and change the dropdown back to Minimize.

Zoom vs Fill: what's the difference?

Zoom has been in macOS since the beginning. It resizes the window to what the app considers its optimal size — which can feel a bit arbitrary. A browser might zoom to fill most of the screen; a small utility might zoom to just a couple hundred pixels.

Fill was added more recently and is more predictable: it always expands the window to take up the entire display, but unlike full-screen mode, it doesn't create a separate Space and doesn't move other windows. You can still see the menu bar and the Dock. If you want a window big without going full-screen, Fill is probably what you want.

What about the green button?

The green traffic-light button in the top-left corner of a window now defaults to full-screen (a separate macOS Space). If you hold Option while clicking it, it zooms instead — which gives you the same result as the double-click Zoom action without leaving your current Space. Knowing both shortcuts lets you choose on the fly.