Modify Icons on DefaultApplication

1929453.ps1

$extension   = ".htm"

$icon = "%SystemRoot%\System32\ddores.dll,-210"

$userChoice  = "HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\${extension}\UserChoice"

try {
    if (Test-Path $userChoice) {
        $progId = (Get-ItemProperty -Path $userChoice -Name "ProgId" -ErrorAction Stop).ProgId
        Write-Host "ProgId for <${extension}> is <${progId}>"
    }
    else {
        Write-Host "No UserChoice key exists for <$extension>"
        exit 1
    }
}
catch {
    Write-Host "Failed to read ProgId for <$extension> $($_.Exception.Message)"
    exit 1
}

if (-not (Test-Path "Registry::HKEY_CLASSES_ROOT\${progId}")) {
    Write-Host "ProgId not registered!"
    exit 1
}

$customProgId = "${progId}_Custom"

if (Test-Path "HKCU:\Software\Classes\${customProgId}") {
    Write-Host "CustomProgId <${customProgId}> already defined!"
    exit 1
} else {
    reg copy "HKCR\${progId}" "HKCU\Software\Classes\${customProgId}" /s /f
    if ($LASTEXITCODE -eq 0) {
        Write-Host "ProgId <${progId}> duplicated to <${customProgId}>"
    } else {
        Write-Host "Duplication of ProgId failed!"
        exit 1
    }
}

$applicationKey = "HKCU:\Software\Classes\${customProgId}\Application"

if (-not (Test-Path $applicationKey)) {
    New-Item -Path $applicationKey -Force | Out-Null
}

$applicationName = (Get-ItemProperty -Path $applicationKey -Name 'ApplicationName' -ErrorAction SilentlyContinue).ApplicationName

if ($null -eq $applicationName) {
    $applicationName = "Custom DefaultApp ($progId)"
} elseif ($applicationName -notmatch '\(Custom\)$') {
    $applicationName = "${applicationName} (Custom)"
}

Write-Host "Updating ApplicationName for <${customProgId}> to <${applicationName}>"

Set-ItemProperty -Path $applicationKey -Name "ApplicationName" -Value $applicationName

$defaultIcon = "HKCU:\Software\Classes\${customProgId}\DefaultIcon"
if (-not (Test-Path $defaultIcon)) {
    New-Item -Path $defaultIcon -Force | Out-Null
}

Write-Host "Updating CustomProgId DefaultIcon"

Set-ItemProperty -Path $defaultIcon -Name "(Default)" -Value $icon

$extensionKey = "HKCU:\Software\Classes\${extension}"
If (-not (Test-Path $extensionKey)) {
    New-Item -Path $extensionKey -Force | Out-Null
}

Write-Host "Updating Extension"

Set-ItemProperty -Path $extensionKey -Name "(Default)" -Value $customProgId

Write-Host "Find a <${extension}> file and use 'Open with' > 'Choose Another App' > select <$applicationName>"

Updated script to modify the ApplicationName on created custom DefaultApp (easier to see in the choose app dialog) and a few checks to make sure registry keys exist.