Text colors in editor sometimes randomly change when scrolling

[bwarren18]

Issue Description

When editing code in an editor window, on very rare occasions, the text coloring that is based on the code content type will randomly change as you scroll down the page. To demonstrate the effect I created a bunch of comment lines between my code.

Other notes:
The Minimap shows the same coloring. There also appears to be 'ghost' characters in it.
The formatting is preserved if copied and pasted into another program, a new message in Outlook for example.
Closing and re-opening VSC fixes the issue.

Another person reported the same issue before and it was closed and suggested to be moved here: microsoft/vscode#120800

Environment Information

Visual Studio Code

Name	Version
Operating System	Windows_NT x64 10.0.19042
VSCode	1.55.2
PowerShell Extension Version	2021.2.2

PowerShell Information

Name	Value
PSVersion	5.1.19041.906
PSEdition	Desktop
PSCompatibleVersions	1.0 2.0 3.0 4.0 5.0 5.1.19041.906
BuildVersion	10.0.19041.906
CLRVersion	4.0.30319.42000
WSManStackVersion	3.0
PSRemotingProtocolVersion	2.3
SerializationVersion	1.1.0.1

Visual Studio Code Extensions

Visual Studio Code Extensions(Click to Expand)

Extension	Author	Version
azurerm-vscode-tools	msazurermtools	0.15.0
Bookmarks	alefragnani	13.0.4
powershell	ms-vscode	2021.2.2
vscode-dotnet-runtime	ms-dotnettools	1.0.0

[SydneyhSmith]

Thanks @bwarren18 we have seen this issue at times as well-- but it is a bit of a tricky one that will take resources to debug--thanks!

[bwarren18]

Thanks @SydneyhSmith, let me know if there is anything I can do to collect more debug information for this.

[andyleejordan]

@bwarren18 Does this only happen when semantic highlighting is enabled?

[bwarren18]

@andschwa Yes. If Semantic Highlighting is set to false it looks fine; the bug reappears if set to true again.

[andyleejordan]

Helpful to know, thank you!

[bwarren18]

I wish I knew a way to consistently reproduce the issue.
It seems to happen when a file is left open in VS code for a while.
Let me know if there is any thing you would like me to check when it happens again. Thanks.

[andyleejordan]

I've seen it occasionally, we have a whole project planned to address the semantic highlighting issues. It was helpful to be able to categorize this. I'm contemplating disabling semantic highlighting by default until we have it working better.

[shelby-carter]

OMG it's a horrible feature! I hate it so much!

For others who struggle with it, just set config to:

"editor.semanticHighlighting.enabled": false,