Hello world script in PowerShell. Should save with UTF-16 BE encoding.

Start-HelloRealWorld.ps1

param(
    [ValidateSet("CUI", "GUI")]
    [string]$RunningStyle,
    [string]$Text
)

### bootstrap
if (-not $RunningStyle) {
    if ((Get-Host).Name -eq "ConsoleHost") {
        Write-Host "Loading..."

        $cmd = '& "{0}" -RunningStyle GUI' -f (&{ $MyInvocation.ScriptName })
        $arg = '-NoLogo -NoProfile -NonInteractive -WindowStyle Hidden -Command ' + $cmd
        Start-Process powershell -WindowStyle Minimized -ArgumentList $arg

        Start-Sleep -Seconds 2
        return
    }

    $RunningStyle = "GUI"
}

function Start-Main {
    [OutputType([Void])]
    [CmdletBinding()]
    param()

    switch ($RunningStyle) {
        "CUI" { Start-Cui }
        "GUI" { Start-Gui }
        Default { throw [NotSupportedException] }
    }
}

function Start-Cui {
    [OutputType([Void])]
    [CmdletBinding()]
    param()

    Write-Host $Text
}

function Start-Gui {
    [OutputType([Void])]
    [CmdletBinding()]
    param()

    try { Add-Type -AssemblyName PresentationCore,PresentationFramework,WindowsBase,System.Windows.Forms }
    catch { throw "Failed to load Windows Presentation Framework assemblies." }

    $xaml = [xml] @'
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Hello Real World!" Height="180" Width="600">
    <Window.Resources>
        <Style x:Key="BaseStyle" TargetType="Control">
            <Setter Property="FontSize" Value="10.5pt" />
        </Style>
        <Style x:Key="SimpleStyle" TargetType="Control" BasedOn="{StaticResource BaseStyle}">
            <Setter Property="Margin" Value="2" />
        </Style>
        <Style TargetType="Label" BasedOn="{StaticResource SimpleStyle}" />
        <Style TargetType="TextBox" BasedOn="{StaticResource SimpleStyle}" />
        <Style TargetType="Button" BasedOn="{StaticResource SimpleStyle}" />
    </Window.Resources>

    <Grid Margin="8,4,8,16">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>

        <Label Content="Text:" Target="{Binding inputText}" Grid.Row="0" Grid.Column="0" />
        <TextBox x:Name="inputText" Grid.Row="0" Grid.Column="1" />
        <Grid HorizontalAlignment="Right" Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2">
            <StackPanel Orientation="Horizontal">
                <Button x:Name="okButton" Content="Run" IsDefault="True" Width="100" />
                <Button x:Name="cancelButton" Content="Exit" IsCancel="True" Width="100" />
            </StackPanel>
        </Grid>
    </Grid>
</Window>
'@

    $global:window = [Windows.Markup.XamlReader]::Load((New-Object Xml.XmlNodeReader $xaml))
    $nsmgr = New-Object Xml.XmlNamespaceManager $xaml.NameTable
    $nsmgr.AddNamespace("x", "http://schemas.microsoft.com/winfx/2006/xaml")
    $xaml.SelectNodes("//*[@x:Name]", $nsmgr) | ForEach-Object {
        Set-Variable -Scope Global -Name $_.Name -Value $window.FindName($_.Name)
    }
    Initialize-Component

    $window.ShowDialog() > $null
}

function Initialize-Component {
    [OutputType([Void])]
    [CmdletBinding()]
    param()

    $window.add_Loaded({
        $inputText.Text = $Text
    })

    $okButton.add_Click({
        [Windows.MessageBox]::Show(
            $window, $inputText.Text, "Result"
            ) > $null
    })
}

Start-Main