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();
                }
            }
        }