Tabs intermittently enter multi-select mode, causing accidental bulk tab closure

Type: Bug

Intermittently, editor tabs switch into a multi-select state where all open tabs appear selected, without any deliberate multi-select action on my part. It seems tied to a modifier key (possibly Alt) being held, but the trigger is inconsistent and I have not been able to reproduce it reliably on demand. The impact is disruptive: if I go to close a single tab while this state is active, all tabs close at once instead of just the intended one. This is especially costly when several tabs are running long-lived processes (in my case, Claude Code sessions in integrated terminals) — closing them ends the session, and I then have to locate and manually restart each one. I haven't found a setting to disable multi-select tab selection or whatever triggers it via a modifier key. Please either stabilize this behavior or add a setting to turn it off entirely. Environment: Windows 11 Pro (10.0.26200)

VS Code version: Code 1.135.0 (08d4889f9ec4a1685d257b9b95de036c8e1ce1e5, 2026-08-25T14:26:52Z)
OS version: Windows_NT x64 10.0.26200
Modes:

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) Ultra 7 255U (14 x 3264)|
|GPU Status|2d_canvas: enabled
GPU0: VENDOR= 0x8086, DEVICE=0x7d41 [Intel(R) Graphics], DRIVER_VENDOR=Intel, DRIVER_VERSION=32.0.101.8724 *ACTIVE*
GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8972
Machine model name:
Machine model version:
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
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off|
|Load (avg)|undefined|
|Memory (System)|31.49GB (14.91GB free)|
|Process Argv|--crash-reporter-id 9ae65c18-8f8a-4d73-9c3f-c01d469605f8|
|Screen Reader|yes|
|VM|0%|
Extensions (5)

Name|Identifier|Author|Version
---|---|---|---
Claude Code for VS Code|anthropic.claude-code|Anthropic|2.1.251
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

A/B Experiments

```
vsliv368:30146709
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
4je02754:31466945
8hhj4413:31478653
cp_cls_t_1081:31454832
conptydll_true:31498968
e9c30283:31461165
46204921:31447328
ei9d7968:31496641
chat:31457767
23c7c724:31520045
ddid_c:31478207
hmra_i5g22:31518061
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
jh5f2457_c:31540921
jbcp_cls_pctr_t:31531130
61138546:31518536
cp_intellij_t_nes:31548657
d7b18187:31526828
ahp-both-windows:31556933
session_8:31532895
ihg5j128:31534457
f412h606:31551416
9gg7f176:31542112
enable_editor_pane_layout:31569726
allow-none:31555437
ac562147:31564510
c7c27ce7:31554789
1h923230:31564177
1532g621_copy:31554320
treatment-23-1:31555779
unuse_dynamic_mcp:31555281
0d8dfbc3:31570291
a1hcc538:31559322
0c1h4866:31566224
vrbsty_fls:31561059
session-archive:31558132
5b8j3302:31564601
mangle-name-control:31572633
lunaclean:31573760
multiv2:31574985
permission_prompt_control:1332567
ccr_pr_nudge_control:1319470
vsc_wsm_t:1340632
eh853263:1355661
auto_mode_control:1359303

```