Safari arbitrarily resizes windows, not related to options in System Settings

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Level 1

8 points

Safari arbitrarily resizes windows, not related to options in System Settings

I'm being driven mad by Safari arbitrarily resizing windows.

To be clear, this is NOT caused by options in System Settings->Desktop & Dock->Windows. All of them have been disabled.

Behavior #1 - If I drag a window that is full size and against the left and top edges of the display towards the middle, Safari will often shorten it by 30-40%.

Interesting Detail - if I drag the window back to top and left edges, resize to full length, then drag back towards the middle again, the shortening behavior does not occur.

Behavior #2 - I often go back to open windows to find they have been tiled to upper left and are tiny. As before, none of the System Settings options are enabled, and in this case no dragging occurred. Safari just decided to do it by itself.

It seems that other people have this problem too, but it gets drowned out by people recommending the Systems Settings choices. This is NOT that.

The behavior is occurring on an M4 MacBook Pro 16" that is often but not always connected to a desktop monitor. The behavior occurs on both displays and both when the MBP is connected to the monitor and when it is not.

Posted on Jul 20, 2026 10:05 AM

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Answer 1

Jul 20, 2026 10:17 AM in response to Lee Chubb

Confirm that all of the settings are off in System Settings > Desktop & Dock:

(More info: Change window tiling settings on Mac - Apple Support)

Be aware that when you hover over the green 'maximize' button in the title bar, there are tiling options that you may be inadvertently selecting:

Have you installed any window arrangers/ managers (Rectangle, Magnet, BetterTouchTool, etc.)? See if the problem is present when you boot in safe mode, which disables 3rd party extensions and performs some system cleanup.

Start up your Mac in safe mode - Apple Support

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Answer 2

leroydouglas

Level 10

205,148 points

Jul 20, 2026 12:57 PM in response to Lee Chubb

Try using a different browser and compare your results.

To trouble shoot further you can:

—A SafeBoot Start up your Mac in safe mode - Apple Support will sort many anomalies

Does a quick disk repair before it fully boots up, and certain system caches get cleared and rebuilt, third party system modifications and system accelerations are disabled temporarily.

Login and test. Reboot as normal and test. Caches get rebuilt automatically.

This test will tell you if third party interference; most extensions etc are not loaded in safe boot mode.

*** (if you are using a wireless keyboard with rechargeable batteries— connect the charging cable, this will make the wired keyboard successful Safe Boot your Mac.)

—Test issue in another user (or guest user) account Change Users & Groups settings on Mac - Apple Support

This will tell you if it a universal issue or isolated to your user/admin account.

unplug all non-essential peripherals when testing

Uninstall all third party apps that are Cleaners/Optimizers/VPN/Anti-Virus

all known to cause issues on the macOS

No insight or resolve—

Call Customer Support (800) MY–APPLE (800–692–7753)

or on line https://getsupport.apple.com/

or call AppleCare Support at 1-800-APLCARE (800-275-2273)

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

Contact Apple Support - Apple Support

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Answer 3

Jul 20, 2026 1:02 PM in response to Lee Chubb

The point is, what you describe is NOT normal behavior. Nor can I replicate it – when I drag Safari windows to the edge of the screen, they do not change size. Ever. Thus the suggestion to re-confirm your settings.

What that suggests is that the problem is with YOUR system, not macOS. What happened when you booted into Safe Mode? Or did you not bother?

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Answer 4

Jul 20, 2026 10:20 AM in response to neuroanatomist

I will add that I have a 16" M4 Pro MBP that I use with an external 5K:2K display (usually in clamshell mode, sometimes using the internal display as well), and I've never seen the behavior you describe with Safari or any other app/Finder windows.

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Answer 5

Lee Chubb Author

Level 1

8 points

Jul 20, 2026 12:43 PM in response to neuroanatomist

Excuse me, but what part of "not related to options in System Settings" was hard to understand? I said it three times, mentioned that it was drowning out other people who have this problem, and still that's what you went to.

And no, neither of the other things you mentioned could possibly be responsible for the issue I am trying to solve.

Solving problems needs a low noise environment. If you don't have useful information to share from direct experience with the problem the person has, please consider just being silent. Your current behavior actually prevents people from finding solutions.

Now, is there anyone out there who might actually have useful information about this (possibly bug related) behavior?

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