Taskbar.cs

using System;
using System.Drawing;
using System.Runtime.InteropServices;

// taskbar api stuff from here:
// http://winsharp93.wordpress.com/2009/06/29/find-out-size-and-position-of-the-taskbar/

public enum TaskbarPosition {
    Unknown = -1,
    Left,
    Top,
    Right,
    Bottom,
}

public sealed class Taskbar {
    private const string ClassName = "Shell_TrayWnd";

    public Rectangle Bounds {
        get;
        private set;
    }
    public TaskbarPosition Position {
        get;
        private set;
    }
    public Point Location {
        get {
            return this.Bounds.Location;
        }
    }
    public Size Size {
        get {
            return this.Bounds.Size;
        }
    }
    //Always returns false under Windows 7
    public bool AlwaysOnTop {
        get;
        private set;
    }
    public bool AutoHide {
        get;
        private set;
    }

    public Taskbar() {
        IntPtr taskbarHandle = User32.FindWindow(Taskbar.ClassName, null);

        APPBARDATA data = new APPBARDATA();
        data.cbSize = (uint)Marshal.SizeOf(typeof(APPBARDATA));
        data.hWnd = taskbarHandle;
        IntPtr result = Shell32.SHAppBarMessage(ABM.GetTaskbarPos, ref data);
        if (result == IntPtr.Zero)
            throw new InvalidOperationException();

        this.Position = (TaskbarPosition)data.uEdge;
        this.Bounds = Rectangle.FromLTRB(
            data.rc.left,
            data.rc.top,
            data.rc.right,
            data.rc.bottom
        );

        data.cbSize = (uint)Marshal.SizeOf(typeof(APPBARDATA));
        result = Shell32.SHAppBarMessage(ABM.GetState, ref data);
        int state = result.ToInt32();
        this.AlwaysOnTop = (state & ABS.AlwaysOnTop) == ABS.AlwaysOnTop;
        this.AutoHide = (state & ABS.Autohide) == ABS.Autohide;
    }
}

public enum ABM : uint {
    New = 0x00000000,
    Remove = 0x00000001,
    QueryPos = 0x00000002,
    SetPos = 0x00000003,
    GetState = 0x00000004,
    GetTaskbarPos = 0x00000005,
    Activate = 0x00000006,
    GetAutoHideBar = 0x00000007,
    SetAutoHideBar = 0x00000008,
    WindowPosChanged = 0x00000009,
    SetState = 0x0000000A,
}

public enum ABE : uint {
    Left = 0,
    Top = 1,
    Right = 2,
    Bottom = 3
}

public static class ABS {
    public const int Autohide = 0x0000001;
    public const int AlwaysOnTop = 0x0000002;
}

public static class Shell32 {
    [DllImport("shell32.dll", SetLastError = true)]
    public static extern IntPtr SHAppBarMessage(
        ABM dwMessage, [In] ref APPBARDATA pData
    );
}

public static class User32 {
    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr FindWindow(
        string lpClassName,
        string lpWindowName
    );
}

[StructLayout(LayoutKind.Sequential)]
public struct APPBARDATA {
    public uint cbSize;
    public IntPtr hWnd;
    public uint uCallbackMessage;
    public ABE uEdge;
    public RECT rc;
    public int lParam;
}

[StructLayout(LayoutKind.Sequential)]
public struct RECT {
    public int left;
    public int top;
    public int right;
    public int bottom;
}