[TeMPOraL]

As I understand it, PowerShell allows you, out of the box, to write some C# code in a string, and then run it. And by C# code I mean regular classes with all the bells and whistles.

[justsomehnguy]

*wink*

    $code = @'
    using System;
    using System.Drawing;
    using System.Runtime.InteropServices;
    using Microsoft.Win32;


    namespace Background 
    {
        public class Setter {
            [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
            private static extern int SystemParametersInfo(int uAction, int uParm, string lpvParam, int fuWinIni);
            [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError =true)]
            private static extern int SetSysColors(int cElements, int[] lpaElements, int[] lpRgbValues);
            public const int UpdateIniFile = 0x01;
            public const int SendWinIniChange = 0x02;
            public const int SetDesktopBackground = 0x0014;
            public const int COLOR_DESKTOP = 1;
            public int[] first = {COLOR_DESKTOP};

            public static void RemoveWallPaper() {
            SystemParametersInfo( SetDesktopBackground, 0, "", SendWinIniChange | UpdateIniFile );
            RegistryKey key = Registry.CurrentUser.OpenSubKey("Control Panel\\Desktop", true);
            key.SetValue(@"WallPaper", 0);
            key.Close();
            }

            public static void SetBackground(byte r, byte g, byte b) {
                RemoveWallPaper();
                System.Drawing.Color color= System.Drawing.Color.FromArgb(r,g,b);
                int[] elements = {COLOR_DESKTOP};
                int[] colors = { System.Drawing.ColorTranslator.ToWin32(color) }; 
                SetSysColors(elements.Length, elements, colors);
                RegistryKey key = Registry.CurrentUser.OpenSubKey("Control Panel\\Colors", true);
                key.SetValue(@"Background", string.Format("{0} {1} {2}", color.R, color.G, color.B));
                key.Close();
            }
        }
    }
    '@

    $null = Add-Type -TypeDefinition $code -ReferencedAssemblies System.Drawing.dll -PassThru

    Function Set-OSDesktopColor {
    param (
        $r,$g,$b
        )

        $null = [Background.Setter]::SetBackground($r,$g,$b)

        }