[html] Mirror cursor devolves into multi-cursor when undoing (ctrl-z)

[rlyczynski]

Issue Type: Bug

1. Open html document and add a tag
   <div></div>
2. Place cursor at the end of the open tag and add a space
   <div ></div>
3. Undo (ctrl-z) once adds a space to close tag (unexpected, but probably an implementation detail of the space special case 🤷‍♂)
   <div ></div >
4. Undo (ctrl-z) twice removes the space from the end of both tags
   <div></div>
5. Add a space and start typing
   <div class="aClass"></div class="aClass">

Expected:
<div class="aClass"></div>

Basically, after the second undo, you're left with a normal multi-cursor. Even if you move the cursor around the document and keep typing the multi-cursor follows.

VS Code version: Code 1.41.1 (26076a4, 2019-12-18T14:58:56.166Z)
OS version: Windows_NT x64 10.0.17763

System Info

Item	Value
CPUs	Intel(R) Xeon(R) E-2176M CPU @ 2.70GHz (12 x 2712)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: enabled rasterization: enabled skia_renderer: disabled_off surface_control: disabled_off surface_synchronization: enabled_on video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	31.74GB (16.78GB free)
Process Argv
Screen Reader	no
VM	0%

Extensions (11)

Extension	Author (truncated)	Version
ng-template	Ang	0.900.3
xml	Dot	2.5.0
json-tools	eri	1.0.2
terraform	mau	1.4.0
vscode-json5	mrm	1.0.0
remote-wsl	ms-	0.41.6
csharp	ms-	1.21.9
vs-keybindings	ms-	0.2.0
debugger-for-chrome	msj	4.12.3
vscode-icons	vsc	9.6.0
better-align	wwm	1.1.6

[octref]

Good catch, although I'm wondering why you would use Cmd-Z instead of backspace in this case.

[rlyczynski]

That's a fair question. I guess its just a habit I've built over time. I like to think that I undo my typos instead of deleting so that unwanted changes aren't left on the "undo stack", but honestly it's probably just a weird quirk that I do.

In fairness this is probably pretty small edge case but something I noticed and the resulting functionality seemed weird so I reported it.

[octref]

This will be fixable if we do #88424.

[octref]

In tomorrow's insiders html.mirrorCursorOnMatchingTag is replaced with editor.renameOnType. The new implementation fixes this issue. You can find more details here: #88424 (comment)