Nested sway does not fullscreen a window, when a window uses fullscreen

[su-sd]

Please fill out the following:

• Sway Version:
  sway version 1.10

• Debug Log:

00:02:51.461 [DEBUG] [sway/tree/arrange.c:262] Usable area for ws: 2256x1458@0,0
00:02:51.461 [DEBUG] [sway/tree/arrange.c:296] Arranging workspace '1' at 0.000000, 0.000000
00:02:51.461 [DEBUG] [sway/tree/arrange.c:76] Arranging 0x7ffd148d0d80 horizontally
00:02:51.461 [DEBUG] [sway/desktop/transaction.c:798] Transaction 0x64bb862f7160 committing with 2 instructions
00:02:51.553 [DEBUG] [sway/desktop/transaction.c:884] Transaction 0x64bb862f7160 is ready
00:02:51.553 [DEBUG] [sway/desktop/transaction.c:694] Applying transaction 0x64bb862f7160

• Configuration File:
  Reproducible with default config

• Description:

• start sway

• start a nested sway session

• run firefox or mpv

• fullscreen the video

• The video is not in fullscreen, the video is at the top left position and takes 2/7 of the screen.
  So the mpv video is bigger in non fullscreen mode than in fullscreen mode.

[emersion]

Your bug report is missing debug logs. Please add a link to the full debug log file.

sway -d >sway.log 2>&1

[su-sd]

@emersion
Here is the debug log of the inner sway, when starting mpv /path/to/video.
nested.txt

What striked my eye is the following line:

Created GL FBO for buffer 1280x720

This is the small window in fullscreen mode. While in non-fullscreen mode, the size Created GL FBO for buffer 2252x1426 is correct.

[su-sd]

I can workaround it by adding the following to the nested sway config:

exec sh -c "sleep 5; swaymsg output '*' scale 1"

Using output '*' scale 1 does not work.
So maybe a startup problem.