Setting focus back to Excel from advanced excel task pane

        private void SetFocusToExcel()
        {
            IntPtr h = APIUtils.GetXLMainWindowHandle(APIUtils.GetDesktopWindow());
            APIUtils.SetFocus(h);
        }

        public class APIUtils
        {
            public static IntPtr GetXLMainWindowHandle(IntPtr DesktopHandle)
            {
                return FindMainWindowInProcess(DesktopHandle, String.Empty, "XLMAIN");
            }

            internal static IntPtr FindMainWindowInProcess(IntPtr HWNDParent, string WindowName, string WindowClass)
            {
                IntPtr FoundWindow = IntPtr.Zero;

                string FindClass = String.Empty;
                string FindName = String.Empty;
                uint WindowProcessID;

                IntPtr tempWindow = GetWindow(HWNDParent, GW_CHILD);
                while ((int)tempWindow > 0)
                {
                    FindName = GetWindowText(tempWindow);
                    FindClass = GetClassName(tempWindow);

                    bool CompareClass = ((FindClass.IndexOf(WindowClass) >= 0) || (WindowClass == String.Empty));
                    bool CompareCaption = ((FindName.IndexOf(WindowName) >= 0) || (WindowName == String.Empty));

                    if (CompareClass && CompareCaption)
                    {
                        GetWindowThreadProcessId(tempWindow, out WindowProcessID);
                        if (GetCurrentProcessId() == WindowProcessID)
                        {
                            FoundWindow = tempWindow;
                            if (IsWindowVisible(FoundWindow))
                            {
                                break;
                            }
                        }
                    }
                    tempWindow = GetWindow(tempWindow, GW_HWNDNEXT);
                }
                return FoundWindow;
            }

            [DllImport("user32.dll")]
            public static extern IntPtr SetFocus(IntPtr hWnd);

            [DllImport("user32.dll")]
            public static extern IntPtr GetDesktopWindow();

            [DllImport("User32.dll", CharSet = CharSet.Auto)]
            public static extern IntPtr GetWindow(IntPtr hwnd, int uCmd);

            [DllImport("user32.dll")]
            public static extern int GetWindowText(IntPtr hwnd,
                [In][Out]StringBuilder lpClassName, int nMaxCount);

            [DllImport("user32.dll")]
            public static extern int GetClassName(IntPtr hwnd,
                [In][Out]StringBuilder lpClassName, int nMaxCount);

            [DllImport("user32.dll")]
            public static extern bool IsWindowVisible(IntPtr hWnd);

            [DllImport("user32.dll", SetLastError = true)]
            public static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

            [DllImport("kernel32.dll")]
            public static extern uint GetCurrentProcessId();

            public static string GetWindowText(IntPtr handle)
            {
                System.Text.StringBuilder lpBuffer = new System.Text.StringBuilder(255);
                if (GetWindowText(handle, lpBuffer, 255) > 0)
                {
                    return lpBuffer.ToString();
                }
                else
                    return "";
            }

            public static string GetClassName(IntPtr handle)
            {
                System.Text.StringBuilder className = new System.Text.StringBuilder(255);
                if (GetClassName(handle, className, 255) > 0)
                {
                    return className.ToString();
                }
                else
                    return "";
            }

            public const int GW_CHILD = 5;
            public const int GW_HWNDNEXT = 2;

        }

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Excel2000, adxxlFormsManager, StdCtrls;

type

  TadxExcelTaskPane1 = class(TadxExcelTaskPane)
    Edit1: TEdit;
    Label1: TLabel;
    procedure Edit1KeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
  private
    { Private declarations }
  protected
    { Protected declarations }
  public
    { Public declarations }
  published
    { Published declarations }
  end;

{NOTE: The adxExcelTaskPane1 variable is intended for the exclusive use
       by the TadxExcelTaskPanesCollectionItem Designer.
       NEVER use this variable for other purposes.}
var
  adxExcelTaskPane1 : TadxExcelTaskPane1;

  function FindMainWindowInProcess(HWNDParent: HWND; WindowName: string; WindowClass: string): HWND;
  function GetWindowCaption(HandleWindow: HWND): string;
  function GetWindowClassName(HandleWindow: HWND): string;

implementation

uses adxWSbcls;

{$R *.DFM}

procedure TadxExcelTaskPane1.Edit1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
var
  H: HWND;
begin
  if (Key = 13) then begin
    H := FindMainWindowInProcess(GetDesktopWindow(), '', 'XLMAIN');
    Windows.SetFocus(H);
  end;
end;

function FindMainWindowInProcess(HWNDParent: HWND; WindowName: string; WindowClass: string): HWND;
var
  FoundWindow: HWND;
  FindClass: string;
  FindName: string;
  WindowProcessID: cardinal;
  tempWindow: HWND;
  CompareClass: boolean;
  CompareCaption: boolean;
begin
  FoundWindow := 0;
  tempWindow := GetWindow(HWNDParent, GW_CHILD);
  while (tempWindow > 0) do begin
    FindName:= GetWindowCaption(tempWindow);
    FindClass:= GetWindowClassName(tempWindow);

    CompareCaption := (pos(WindowName, FindName) > 0) or (WindowName = '');
    CompareClass := (pos(WindowClass, FindClass) > 0) or (WindowClass = '');

    if (CompareClass and CompareCaption) then begin
      GetWindowThreadProcessId(tempWindow, @WindowProcessID);
      if (GetCurrentProcessId() = WindowProcessID) then begin
        FoundWindow := tempWindow;
        if (IsWindowVisible(FoundWindow)) then begin
          break;
        end;
      end;
    end;
    tempWindow := GetWindow(tempWindow, GW_HWNDNEXT);
  end;
  result := FoundWindow;
end;

function GetWindowCaption(HandleWindow: HWND): string;
var
  lpBuffer : array [0..256-1] of Char;
begin
  Result:= '';
  if GetWindowText(HandleWindow, @lpBuffer, 256) > 0 then
    Result:= StrPas(lpBuffer);
end;

function GetWindowClassName(HandleWindow: HWND): string;
var
  lpBuffer : array [0..256-1] of Char;
begin
  Result:= '';
  if GetClassName(HandleWindow, @lpBuffer, 256) > 0 then
    Result:= StrPas(lpBuffer);
end;

initialization
  RegisterClass(TPersistentClass(TadxExcelTaskPane1));

finalization
end.