按下Messagebox上的帮助按钮时未触发事件

Question

我有一个C#应用程序,我正在使用带有帮助按钮的Messagebox.Show,根据微软的例子http://msdn.microsoft.com/en-us/library/szwxe9we.aspx

我将事件添加到表单中,但按下帮助按钮从不触发事件 - 然而按表格上的F1键.即使完全采用微软的例子也不会引发这一事件.整个代码如下.我有什么想法吗？

还有一个帖子,有人注意到了这一点.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            DialogResult r = AlertMessageWithCustomHelpWindow();
        }
        // Display a message box with a Help button. Show a custom Help window
        // by handling the HelpRequested event.
        private DialogResult AlertMessageWithCustomHelpWindow()
        {
            // Handle the HelpRequested event for the following message.
            this.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.Form1_HelpRequested);

            this.Tag = "Message with Help button.";

            // Show a message box with OK and Help buttons.
            DialogResult r = MessageBox.Show("Message with Help button.",
                                              "Help Caption", MessageBoxButtons.OK,
                                              MessageBoxIcon.Question,
                                              MessageBoxDefaultButton.Button1,
                                              0, true);

            // Remove the HelpRequested event handler to keep the event
            // from being handled for other message boxes.
            this.HelpRequested -= new System.Windows.Forms.HelpEventHandler(this.Form1_HelpRequested);

            // Return the dialog box result.
            return r;
        }

        private void Form1_HelpRequested (System.Object sender, System.Windows.Forms.HelpEventArgs hlpevent)
        {
            // Create a custom Help window in response to the HelpRequested event.
            Form helpForm = new Form();

            // Set up the form position, size, and title caption.
            helpForm.StartPosition = FormStartPosition.Manual;
            helpForm.Size = new Size(200, 400);
            helpForm.DesktopLocation = new Point(this.DesktopBounds.X +
                                                  this.Size.Width,
                                                  this.DesktopBounds.Top);
            helpForm.Text = "Help Form";

            // Create a label to contain the Help text.
            Label helpLabel = new Label();

            // Add the label to the form and set its text.
            helpForm.Controls.Add(helpLabel);
            helpLabel.Dock = DockStyle.Fill;

            // Use the sender parameter to identify the context of the Help request.
            // The parameter must be cast to the Control type to get the Tag property.
            Control senderControl = sender as Control;

            helpLabel.Text = "Help information shown in response to user action on the '" +
                              (string)senderControl.Tag + "' message.";

            // Set the Help form to be owned by the main form. This helps
            // to ensure that the Help form is disposed of.
            this.AddOwnedForm(helpForm);

            // Show the custom Help window.
            helpForm.Show();

            // Indicate that the HelpRequested event is handled.
            hlpevent.Handled = true;

        }


    }
}

Answer 1

走线

DialogResult r = AlertMessageWithCustomHelpWindow();

在 Form1 构造函数之外 - 也许将其放在主窗体上的按钮单击处理程序中。看起来您正在使用 MessageBox.Show() 阻止 UI 线程，从而停止显示帮助对话框。