C#

public class TBAppBar
        {
            [DllImport("shell32", EntryPoint = "SHAppBarMessage", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
            private static extern int GetAppBarMessage(int dwMessage, ref APPBARDATA pData);
            [DllImport("shell32", EntryPoint = "SHAppBarMessage", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
            private static extern int SetAppBarMessage(int dwMessage, ref APPBARDATA pData);

            //Get Message Sent By App Bar

            //Send Message To App BAr

            private struct APPBARDATA
            {
                //AppBar Structure
                public int cbSize;
                public int hwnd;
                public int uCallbackMessage;
                public int uEdge;
                public Rectangle rc;
                public int lParam;
            }

            //Get Current State
            private const Int32 ABM_GETSTATE = 0x4;
            //Get TaskBar Position
            private const Int32 ABM_GETTASKBARPOS = 0x5;
            //Apply Setting(s)
            private const Int32 ABM_SETSTATE = 0xa;
            //Autohide
            private const Int32 ABS_AUTOHIDE = 0x1;
            //Always on Top
            private const Int32 ABS_ALWAYSONTOP = 0x2;

            private bool TBAppBAutoHide;

            private bool TBAppBarAlwaysOnTop;
            public TBAppBar()
            {
                this.GetState();
                //Get Current State
            }


            private void GetState()
            {
                APPBARDATA AppBarSetting = new APPBARDATA();
                //What Setting?

                AppBarSetting.cbSize = Marshal.SizeOf(AppBarSetting);
                //Initialise

          --->  Int32 AppBarState = GetAppBarMessage(ABM_GETSTATE, AppBarSetting); <---
                //Get Current State

                switch (AppBarState)
                {
                    case 0:
                        //Nothing Set
                        TBAppBAutoHide = false;
                        TBAppBarAlwaysOnTop = false;

                        break;
                    case ABS_ALWAYSONTOP:
                        //Always On Top
                        TBAppBAutoHide = false;
                        TBAppBarAlwaysOnTop = true;

                        break;
                    default:
                        TBAppBAutoHide = true;
                        //AutoHide
                        break;
                }
            }

            //Apply Settings
            private void SetState()
            {

                APPBARDATA AppBarSetting = new APPBARDATA();
                //Setting We Want To Apply
                AppBarSetting.cbSize = Marshal.SizeOf(AppBarSetting);
                //Initialise

                if (this.AutoHide)
                {
                    AppBarSetting.lParam = ABS_AUTOHIDE;
                    //AutoHide
                }

                if (this.AlwaysOnTop)
                {
                    AppBarSetting.lParam = AppBarSetting.lParam | ABS_ALWAYSONTOP;
                    //Always On Top
                }
                SetAppBarMessage(ABM_SETSTATE, AppBarSetting);
            }

            public bool AutoHide
            {
                //Autohide
                get { return TBAppBAutoHide; }
                set
                {
                    TBAppBAutoHide = value;
                    this.SetState();
                }
            }

            public bool AlwaysOnTop
            {
                //Always On Top
                get { return TBAppBarAlwaysOnTop; }
                set
                {
                    TBAppBarAlwaysOnTop = value;
                    this.SetState();
                }
            }
        }

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
       {
           //Do Intensive Work
           ArgumentClass backGroundCls = e.Argument as ArgumentClass;

           //Now you can do whatever you want to do with passed arguments

           int ctr=0;
           do
           {
               ctr++;
               backgroundWorker1.ReportProgress(ctr);
           } while (ctr < 10000000);

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Testing_Trig
{
    class Program
    {
        static void Main(string[] args)
        {
            Double Radian = (Math.PI / 180);
            Double count = 0;
            int[] array = {1,0};
            for (int i = 0; i < 2; i++)
            {
                if (array[i] == 1) count += Math.Tan(Radian);//POSITIVE COUNT = 0.0174550649282176
                if (array[i] == 0) count += Math.Tan(-Radian);//NEGATIVE COUNT = -0.0174550649282176
            }
            //EXPECTING POSITVE AND NEGATIVE TO CANCELL EACH OTHER AND COUNT = 0, BUT GOT THE FOLLOWING:
            Console.WriteLine("count = {0}", count);//I DON'T UNDERSTAND WHY = -4.06575814682064E-20
            //I REALLY NEED TO UNDERSTAND WHAT HAPPEN. CAN SOMEONE PLEASE EXPLAIN?
        }
    }
}