Docs-preview: Side-by-side markdown code and preview erratically jumps around when editing code

[dime10]

Issue Type: Bug

1. Open a markdown file with some content longer than the window height.

2. Open the markdown preview (Ctrl+Shift+v) and slide it to the right half of the editor (side-by-side view).

3. Edit the markdown file.

Expected: The code view should always stay in the same position unless the user scrolls the code or preview.

Actual: Just typing in the code makes the code view and preview jump arround erratically.

Extension version: 0.3.57
VS Code version: Code 1.56.2 (054a9295330880ed74ceaedda236253b4f39a335, 2021-05-12T17:13:13.157Z)
OS version: Windows_NT x64 10.0.19043

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz (4 x 2808)
GPU Status	2d_canvas: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: enabled opengl: enabled_on rasterization: enabled skia_renderer: enabled_on video_decode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	15.92GB (8.27GB free)
Process Argv	--crash-reporter-id 2bc48bd2-b0c0-48f2-8d99-7cb177a61206
Screen Reader	no
VM	0%

A/B Experiments

vsins829:30139715
vsliv368:30146709
vsreu685:30147344
vspor879:30202332
vspor708:30202333
vspor363:30204092
vspre833cf:30267465
vshan820:30294714
vscorecescf:30290706
vscus158:30286553
vscod805:30301674

[bharney0]

@dime10 do you have an example markdown page in a repo we can repro this issue with?

[amineAUPEC]

same bug

[dime10]

@bharney0 Sure, this file for example seems especially egregious.

[edburns]

THIS IS KILLING ME!

[edburns]

@bharney0 This PR shows it really well. (Microsoft internal)

[guardrex]

I'd like to be able to merely thumb-up the OP on this, but this makes the extension very difficult to use, and this issue has been here since 2001. How about fixing it?

Merely scrolling the preview panel or the code (not just editing the markdown) causes this problem that jumps you back in the article. Closing and re-opening the preview helps, and scrolling slowly works a lot better than fast scrolling, but the problem remains with either the preview panel or the markdown jumping you back up as you scroll down the article.