White lines appear around the screen when in fullscreen on macos 26 dark appearance

[flysn0w]

mpv Information

mpv v0.41.0-dev-g88ac54b95 Copyright © 2000-2026 mpv/MPlayer/mplayer2 projects
 built on Mar 10 2026 08:00:23
libplacebo version: v7.360.0
FFmpeg version: 8.0.1
FFmpeg library versions:
   libavcodec      62.11.100
   libavdevice     62.1.100
   libavfilter     11.4.100
   libavformat     62.3.100
   libavutil       60.8.100
   libswresample   6.1.100
   libswscale      9.1.100

Other Information

- macOS version:26.3.1
- Source of mpv:nightly.link/mpv-player/mpv/workflows/build/master
- Latest known working version:0.41.0
- Issue started after the following happened:dark appearance，native-fs=no，fullsreen

Reproduction Steps

Turn on dark appearance on macos 26 arm
native-fs=no in mpv.conf
open mpv in fullscreen

Expected Behavior

there are no white lines around the screen when in fullscreen

Actual Behavior

there are white lines on all sides of the screen in fullscreen

Log File

no need

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• I tested and confirmed that the issue exists with the latest release version or newer.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

[flysn0w]

This is an issue with the program’s appearance; it occurs even when videos are not playing, so it hasn’t been reported before and not repeated

[Akemi]

without testing or looking into this, if native-fs=no is indeed the problem and the native fullscreen works, it's again something Apple broke. it's a bit like fighting windmills, doing something that Apples doesn't want us to doing.

i don't think i will look into this any time soon, since it works on macOS before 26 and i am still on 15.

[low-batt]

@Akemi I had intended to check if mpv had this problem and if so, propose a fix, but as usual got interrupted and have been so overloaded that I nearly forgot about this problem. Sorry!

In the dreadful bug filled macOS Big Sur (11) Apple broke custom full screen implementations by disallowing use of fullscreen in a window's styleMask, reserving it for exclusive use by AppKit's own native implementation (toggleFullScreen). Apps with their own custom fullscreen implementations had to workaround this by guessing what changes the fullscreen style applied to the window and manually applying those changes when running under the dreadful bug filled macOS Big Sur release as well as following releases as Apple still has not fixed some of the defects introduced in Big Sur.

In the horrendous awful terrible bug filled macOS Tahoe (26) release Apple made changes to enhance visual depth. This included making a window's shadow more pronounced. This has revealed the workaround for the dreadful bug filled macOS Big Sur release denying access to the fullscreen style is missing code to remove the window's shadow when in full screen mode. So shockingly this actually isn't a defect in the horrendous awful terrible bug filled macOS Tahoe release, merely more fallout from the dreadful bug filled macOS Big Sur release.

IINA also had this problem (issue iina/iina#5783).

[flysn0w]

[low-batt]

@flysn0w I'm confused by the comment that is just a screenshot. Did you try the mpv with the proposed fix? Apps with the fix built for ARM or Intel can be found here.

[flysn0w]

@flysn0w I'm confused by the comment that is just a screenshot. Did you try the mpv with the proposed fix? Apps with the fix built for ARM or Intel can be found here.

I have test this mpv-v0.41.0-dev-g153cf5bc6-pr17594-23162067778-macos-26-arm and can confirm this fixes the issue. As a regular user, thank you for your work.