add-type @"
using System;
using System.Runtime.InteropServices;
namespace Huddled {
    public class Tricks {
        [DllImport("user32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);

        public static void ShowWindow(IntPtr hWnd) {
            ShowWindowAsync(hWnd,5);
        }
        public static void HideWindow(IntPtr hWnd) {
            ShowWindowAsync(hWnd,0);
        }
    }
}
"@

Get-Process | Where MainWindowHandle | % { [Huddled.Tricks]::HideWindow( $_.MainWindowHandle ) }