How do I use SetWindowTextW in Win32 using PowerShell?

I’m trying to use PowerShell to change a Window title to display emojis.

I can change the Window title of a process (that has a window) using…

Add-Type -TypeDefinition @"
using System;
using System.Runtime.InteropServices;

public static class Win32 {
  [DllImport("User32.dll", EntryPoint="SetWindowText")]
  public static extern int SetWindowText(IntPtr hWnd, string strTitle);
}
"@

$MyNotepadProcess = start-process notepad -PassThru

[Win32]::SetWindowText($MyNotepadProcess.MainWindowHandle, 'My Title')

But using SetWindowTextW just garbles the output…

Add-Type -TypeDefinition @"
using System;
using System.Runtime.InteropServices;

public static class Win32 {
  [DllImport("User32.dll", EntryPoint="SetWindowTextW")]
  public static extern int SetWindowTextW(IntPtr hWnd, string strTitle);
}
"@

$MyNotepadProcess = start-process notepad -PassThru

[Win32]::SetWindowTextW($MyNotepadProcess.MainWindowHandle, 'My Title')

One issue I think I have, is that SetWindowTextW only accept wide string, but I don’t know how to provide that as input.
And then I need to add the emojis using the UniCode numbers as in `u{1F600} (that’s a 🙂 too you).
(See Get Started with Win32 and C++ – Working with Strings)

>Solution :

The simplest way to ensure that the Unicode version of a WinAPI function is called properly is to:

• Add CharSet=CharSet.Unicode to the [DllImport] attribute.

• Omit the W suffix from the function name.

// Note the use of "CharSet=CharSet.Unicode" and 
// the function name *without suffix*
[DllImport("User32.dll", CharSet=CharSet.Unicode)]
public static extern int SetWindowText(IntPtr hWnd, string strTitle);

This ensures that SetWindowTextW, i.e. the Unicode implementation of the function is called, and that .NET marshals the .NET string essentially as-is as as a native LPCWSTR string, i.e. as a null-terminated array of Unicode code units.