Background color leaking to next scrolled line

Steps to reproduce

Issue this command on the last line of your window so that scrolling is taking place:

Write-Host "Bebop" -BackgroundColor Green -ForegroundColor Black

Expected behavior

The line below the “Bebop” line is clean (i.e. what was done with Write-Host doesn’t leak into the following line)

Actual behavior

The line is painted green

Environment data

PSVersion                      7.1.3
PSEdition                      Core
GitCommitId                    7.1.3
OS                             Microsoft Windows 10.0.19042
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

[Fred-Vatin]

Similar issues or duplicates

#14686 #11267

Setup

I can reproduce.

Name                           Value
----                           -----
PSVersion                      7.1.3
PSEdition                      Core
GitCommitId                    7.1.3
OS                             Microsoft Windows 10.0.19041
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Tested with cleaned session from user installed modules and without PSReadline.

PS>gmo | select name, version

Name                            Version
----                            -------
Microsoft.PowerShell.Management 7.0.0.0
Microsoft.PowerShell.Utility    7.0.0.0

Step to reproduce

I you run this below code directly or via a file.ps1, the result is the same.

[Enum]::GetValues([ConsoleColor]) |
ForEach-Object {
   $color = $_.ToString().Trim()
   if (($color -like 'dark*') -or ($color -like 'black')) {
   	Write-Host 'test' -BackgroundColor Black
   	Write-Host "$color" -ForegroundColor $color
   	Write-Host "$color" -ForegroundColor White -BackgroundColor $color
   } else {
   	Write-Host 'test' -BackgroundColor Black
   	Write-Host "$color" -ForegroundColor $color
   	Write-Host "$color" -ForegroundColor Black -BackgroundColor $color
   }
}

Results

Rendering in console or in WT. Look at the bottom of the window. I suspect the scroll cause the issue as mentioned in one of the issue mentioned before.

As we can see, write-host with -BackgroundColor option fills the entire line with the color. For some reason, the line length seems to be longer than the console width and leak to the the next scroll line. This is solved when resizing console width.

Here is running command colortool -c

Expectation

First, documentation doesn’t mention write-host with -BackgroundColor is supposed to fill the entire line instead of the object alone. This needs to be clarified.

Secondly, it seems that line length seen by write-host is longer than the console width. In any case, background color should not line break.

Workaround (almost)

Use -NoNewline if using -BackgroundColor.

[Enum]::GetValues([ConsoleColor]) |
ForEach-Object {
	$color = $_.ToString().Trim()
	if (($color -like 'dark*') -or ($color -like 'black')) {
		Write-Host "`n$color" -ForegroundColor $color
		Write-Host "$color" -ForegroundColor White -BackgroundColor $color -NoNewline
	} else {
		Write-Host "`n$color" -ForegroundColor $color
		Write-Host "$color" -ForegroundColor Black -BackgroundColor $color -NoNewline
	}
}

This will produce non apparent bug. Only the object is filled with background color. But when resizing window, the all line is filled.

Note

This problem does not occur in the integrated terminal for VSCode.

[fflaten]

Still an issue in 7.3 previews. Able to repro in vscode integrated console, conhost and windows terminal. This is one of the few things where Windows PowerShell 5.1 is superior 🙂