Clear-Host does not clear the entire Windows Terminal after running Lee's rick-roll

Steps to reproduce

iex (New-Object Net.WebClient).DownloadString("http://bit.ly/e0Mw9w")

Expected behavior

After terminating the rick-roll, executing clear-host should clear the entire console but it does not.

Actual behavior

This is my console right after executing clear-host:

Notice that there is still text at the bottom of the screen. I don’t see this problem in the PowerShell console. It appears that the script resets what PS thinks is the terminal size. That actually resets the console size but that does not impact the Windows Terminal tab size. Before running the script, PS sees the WIndows Terminal buffer/window size as:

BufferSize            : 121,68
WindowSize            : 121,68

After the script runs (and is aborted by pressing Q)) it is:

BufferSize            : 83,45
WindowSize            : 83,45

It would appear Clear-Host is operating on bad buffer/size data.

Environment data

Name                           Value
----                           -----
PSVersion                      7.2.0-preview.5
PSEdition                      Core
GitCommitId                    7.2.0-preview.5
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

Related: #644

[rkeithhill]

@237dmitry ignore the script. This issue is really about why the following breaks Clear-Host functionality in Windows Terminal:

dir C:\Windows
$host.UI.RawUI.WindowSize = New-Object System.Management.Automation.Host.Size 83,45
Clear-Host

[rkeithhill]

Yup, a simple repro is to dump a bunch of text to the terminal (dir ~) and then execute:

dir C:\Windows
$host.UI.RawUI.WindowSize = New-Object System.Management.Automation.Host.Size 83,45
Clear-Host