PDF Mosaic: How to add Hide action in PDF document

using PDFMosaic;
using System;
 
namespace HideAction
{
    class HideAction
    {
        static void Main()
        {
            PDFDocument document = new PDFDocument();
            PDFPage page = new PDFPage(PDFPaperFormat.A4);
 
            PDFEditBox editBox = new PDFEditBox(20, 40, 80, 20, "edit1");
            editBox.Text = "Text";
            page.Annotations.Add(editBox);
 
            PDFComboBox comboBox = new PDFComboBox(20, 70, 60, 20, "comboBox1");
            comboBox.Items.Add("Item 1");
            comboBox.Items.Add("Item 2");
            comboBox.Text = "Combo Box";
            comboBox.Font.Size = 8;
            page.Annotations.Add(comboBox);
 
            PDFPushButton showButton = new PDFPushButton(20, 100, 40, 15, "btn1");
            showButton.Caption = "Show";
            showButton.Font.Size = 8;
            page.Annotations.Add(showButton);
 
            PDFPushButton hideButton = new PDFPushButton(70, 100, 40, 15, "btn2");
            hideButton.Caption = "Hide";
            hideButton.Font.Size = 8;
            page.Annotations.Add(hideButton);
 
            PDFHideAction hideAction = new PDFHideAction(true);
            hideAction.Fields.Add(editBox);
            hideAction.Fields.Add(comboBox);
            hideButton.OnActivated = hideAction;
 
            PDFHideAction showAction = new PDFHideAction(false);
            showAction.Fields.Add(editBox);
            showAction.Fields.Add(comboBox);
            showButton.OnActivated = showAction;
 
            document.Pages.Add(page);
            document.Save("HideAction.pdf", true);
        }
    }
}