Unable to scroll horizontally in VScode when secondary panel is open

Type: Bug

I am seeing that when the secondary side panel is open, the diff view doesn't allow horizontal scrolling. This has been happening since the last release. I am not exactly sure of the reason.

VS Code version: Code 1.138.0 (7debcd0e2acdea1c52de81bf9ee1620444407dda, 2026-09-15T07:24:32Z)
OS version: Darwin arm64 25.6.0
Modes:

Attaching a screen recording for the same below:

**Steps to reproduce:**
1. Ensure you are in a git repository
2. Update a file with one line much longer than you visible text width(probably something like lorem ipsum)
3. Open the secondary side bar
4. Go to the diff view & try to scroll to the right to see the entire diff

Major issues observed are as below:
1. horizontal scroll is disabled
2. unable to see the diff view
3. unable to see the active cursor position due to the side scroll not happening

System Info

|Item|Value|
|---|---|
|CPUs|Apple M3 Pro (12 x 2400)|
|GPU Status|2d_canvas: enabled
GPU0: VENDOR= 0x106b [Google Inc. (Apple)], DEVICE=0x0000 [ANGLE (Apple, ANGLE Metal Renderer: Apple M3 Pro, Version 26.7 (Build 25G229))], DRIVER_VENDOR=Apple, DRIVER_VERSION=26.7 *ACTIVE*
Machine model name: Mac
Machine model version: 15.7
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: enabled_on
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off|
|Load (avg)|3, 3, 4|
|Memory (System)|36.00GB (0.12GB free)|
|Process Argv|--crash-reporter-id 2dcb63c7-3d66-4e08-bad2-d946fe4da2b6|
|Screen Reader|no|
|VM|0%|
Extensions (22)

Name|Identifier|Author|Version
---|---|---|---
Better Comments|aaron-bond.better-comments|aaron-bond|3.0.2
Bookmarks|alefragnani.bookmarks|alefragnani|14.1.1
Claude Code for VS Code|anthropic.claude-code|Anthropic|2.1.263
ESLint|dbaeumer.vscode-eslint|dbaeumer|3.0.34
Git History|donjayamanne.githistory|donjayamanne|0.6.20
Prettier - Code formatter|esbenp.prettier-vscode|esbenp|12.4.0
Jest / Vitest Runner|firsttris.vscode-jest-runner|firsttris|0.4.148
GitHub Pull Requests|github.vscode-pull-request-github|GitHub|0.166.1
Peacock|johnpapa.vscode-peacock|johnpapa|4.4.1
Seti folder|l-igh-t.vscode-theme-seti-folder|l-igh-t|1.3.0
Template String Converter|meganrogge.template-string-converter|meganrogge|0.6.1
Highlight on Copy|mguellsegarra.highlight-on-copy|mguellsegarra|1.1.6
Container Tools|ms-azuretools.vscode-containers|ms-azuretools|2.5.1
Python Debugger|ms-python.debugpy|ms-python|2026.6.0
Python|ms-python.python|ms-python|2026.4.0
Pylance|ms-python.vscode-pylance|ms-python|2026.3.1
Python Environments|ms-python.vscode-python-envs|ms-python|1.36.0
Ollama|ollama.ollama|Ollama|0.0.9
Git Prefix|srmeyers.git-prefix|srmeyers|1.3.3
Quokka.js|wallabyjs.quokka-vscode|WallabyJs|1.0.769
Pretty TypeScript Errors|yoavbls.pretty-ts-errors|YoavBls|0.8.7
Markdown All in One|yzhang.markdown-all-in-one|yzhang|3.6.3

A/B Experiments

```
vsliv368cf:30146710
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31463988
aj953862:31281341
envsactivate1:31551504
cloudbuttont:31379625
3efgi100_wstrepl:31403338
ec5jj548:31422691
cp_cls_t_966_ss:31526232
4je02754:31572277
8hhj4413:31478653
ge8j1254_inline_auto_hint_haiku:31490510
cp_cls_c_1081:31454833
conptydll_true:31498968
e9c30283:31461165
46204921:31447328
ei9d7968:31496641
chat:31457767
8hig5102:31480529
89g7j272:31518289
i2gc6536:31499202
52612955:31516516
ddid_t:31478206
hmra_i5g22:31518061
l_j1ci3728:31580635
7df3h592:31512476
cp_cls_t_1082:31535311
logging_enabled_new:31498466
db5d2638:31499441
jb_cp_cls_t_632:31543129
56dj4588:31512888
32d76977:31512328
ha629193:31508444
a1ije391_t:31540920
jbcp_cls_pctr_t:31531130
cp_intellij_t_nes:31548657
jf4hg949:31526829
ahp-both-windows:31556933
ihg5j128:31534457
9gg7f176:31542112
sandbox-ui-on-2:31543161
enable_editor_pane_layout:31569726
allow-none:31555437
ac562147:31564510
c7c27ce7:31554789
1h923230:31564177
treatment-23-1:31555779
unuse_dynamic_mcp:31555281
0d8dfbc3:31570291
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session-archive:31558132
5b8j3302:31564601
autotiers:31584978
mangle-name-control:31572633
allow-signed-out:31584137
intellij_nes_preview_t:31580086
39a5d156:31574986
2bfb8b39:31576696
soft:31581111
aw-autom-on:31583758
revealsession_treatment_7ed7e840:31582194
4ab0b639:31584543
codex-agent-host-stable-control:31585316
permission_prompt_treatment:1332566
ccr_pr_nudge_auto_review:1319472
vsc_wsm_c:1340633
h5e14506_copy:1348995
cfee5631:1379228
3aced641:1389836

```