tmux thinks terminal is less wide in terminal window

Type: Bug

This just started happening after I upgraded to VS Code 1.87.0. I normally use tmux in my terminal window. I do remote develpment running VS Code on Windows 11 locally, and my remote machine is Ubuntu 20. When I have two VS Code windows open with terminals, if I resize one (making it skinnier), the other shows dots and the working area also gets skinnier so they both show the same (smaller) width. If I close the skinnier instance, the remaining instance grows to the full terminal width again. This is as expected, and I belive working correctly.

Starting with the latest VS Code release, if I have just a single window, the terminal opens normally, but then, soon (a few minutes) after, it sometimes switches to a a much skinner tmux view (e.g., 40 characters instead of 100, but I didn't count), as if I had another (skinny) terminal open, but I don't. It doesn't always happen, but I've seen it a few times since upgrading. Once, it happened (a few minutes) after I opened a second instance of VS Code. It looked like both instances were constrained by some 3rd (imaginary) instance. When I closed the 2nd instance, the remaining instance regained its full width. This would imply something in the 2nd instance was causing it, or reporting a smaller width, even though the terminal window I could see was full width. But this also seems to happen when I only have one instance of VS Code running (and nothing else should have tmux terminals to my remote machine).

VS Code version: Code 1.87.0 (019f4d1419fbc8219a181fab7892ebccf7ee29a2, 2024-02-27T23:41:44.469Z) OS version: Windows_NT x64 10.0.22631 Modes: Remote OS version: Linux x64 5.4.0-172-generic Remote OS version: Linux x64 5.4.0-172-generic

System Info

|Item|Value| |---|---| |CPUs|11th Gen Intel(R) Core(TM) i7-11370H @ 3.30GHz (8 x 3302)| |GPU Status|2d_canvas: enabled
canvas_oop_rasterization: enabled_on
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
video_decode: enabled
video_encode: enabled
vulkan: disabled_off
webgl: enabled
webgl2: enabled
webgpu: enabled| |Load (avg)|undefined| |Memory (System)|15.84GB (1.43GB free)| |Process Argv|--file-uri vscode-remote://ssh-remote%2Bandy-server/opt/gpudb-dev/server-master.code-workspace --crash-reporter-id 04ee8daf-1cd4-4053-981f-c1eb77f02499| |Screen Reader|no| |VM|0%| |Item|Value| |---|---| |Remote|SSH: andy-server| |OS|Linux x64 5.4.0-172-generic| |CPUs|Intel(R) Xeon(R) CPU X5650 @ 2.67GHz (24 x 2933)| |Memory (System)|70.76GB (46.39GB free)| |VM|0%| |Item|Value| |---|---| |Remote|SSH: andy-server| |OS|Linux x64 5.4.0-172-generic| |CPUs|Intel(R) Xeon(R) CPU X5650 @ 2.67GHz (24 x 2933)| |Memory (System)|70.76GB (46.38GB free)| |VM|0%|

Extensions (39)

Extension|Author (truncated)|Version ---|---|--- Bookmarks|ale|13.4.2 remotehub|Git|0.62.0 better-cpp-syntax|jef|1.17.2 vscode-cudacpp|kri|0.1.1 l13-diff|L13|1.3.5 remote-ssh|ms-|0.109.0 remote-ssh-edit|ms-|0.86.0 remote-wsl|ms-|0.86.0 vscode-remote-extensionpack|ms-|0.25.0 azure-repos|ms-|0.38.0 remote-explorer|ms-|0.4.3 remote-repositories|ms-|0.40.0 remote-server|ms-|1.5.1 Bookmarks|ale|13.4.2 githistory|don|0.6.20 gitlens|eam|14.8.2 vscode-javac|geo|0.2.46 l13-diff|L13|1.3.5 restructuredtext-pack|lex|1.0.3 git-graph|mhu|1.30.0 debugpy|ms-|2024.2.0 isort|ms-|2023.10.1 python|ms-|2024.2.1 vscode-pylance|ms-|2024.2.3 cpptools|ms-|1.19.5 cpptools-extension-pack|ms-|1.3.0 hexeditor|ms-|1.9.14 fabric8-analytics|red|0.9.2 java|red|1.28.1 vscode-yaml|red|1.14.0 simple-rst|tro|1.5.4 kb-macro|tsh|0.13.13 intellicode-api-usage-examples|Vis|0.2.8 vscodeintellicode|Vis|1.2.30 vscode-java-debug|vsc|0.56.2 vscode-java-dependency|vsc|0.23.5 vscode-java-pack|vsc|0.25.15 vscode-java-test|vsc|0.40.1 vscode-maven|vsc|0.44.0 (2 theme extensions excluded)

A/B Experiments

``` vsliv368cf:30146710 vspor879:30202332 vspor708:30202333 vspor363:30204092 vscorecescf:30445987 vscod805:30301674 binariesv615:30325510 vsaa593:30376534 py29gd2263:30899288 vscaac:30438847 c4g48928:30535728 azure-dev_surveyone:30548225 962ge761:30959799 pythongtdpath:30769146 welcomedialogc:30910334 pythonidxpt:30866567 pythonnoceb:30805159 asynctok:30898717 pythontestfixt:30902429 pythonregdiag2:30936856 pyreplss1:30897532 pythonmypyd1:30879173 pythoncet0:30885854 2e7ec940:30968132 pythontbext0:30879054 accentitlementsc:30887149 dsvsc016:30899300 dsvsc017:30899301 dsvsc018:30899302 cppperfnew:30979542 d34g3935:30971562 a89i1917:30973842 bg6jg535:30979843 78248357:30976999 dsvsc020:30976470 ```

microsoft / vscode

tmux thinks terminal is less wide in terminal window #206920