转：悬挂窗口

所谓悬挂窗口，就是类似QQ聊天工具的一个功能，当窗口放到桌面的上边界时自动收缩成一个小条隐藏起来；而一旦鼠标再次接触到上述边界的时候，窗口又会自动展开。

实现方法有两类，一是窗口内实现悬挂，在窗口内创建一个小的Panel，正常时不可见，在悬挂是显示，
悬挂时设置窗口标题栏不显示和窗口高度为该Panel高度；二是单独窗口悬挂，创建新的窗口作为悬挂时的显示条，同时隐藏掉主窗口。

一、窗口内实现悬挂
在LocationChanged事件内判断是否到桌面上边界，通过定时器判断当前鼠标位置（System.Windows.Forms.Control.MousePosition）是否离开窗口区域，或者进入窗口区域。

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

namespace Demo
{
    /// <summary>
    /// 方法一：窗口内实现悬挂
    /// </summary>
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            pnlHangBar.Visible = false;
            m_NomalHeight = Height;
            m_IsHange = false;
            timer1.Enabled = true;
            timer1.Interval = 200;
            timer1.Tick += new EventHandler(timer1_Tick);
        }

        /// <summary>
        /// 窗体正常高度
        /// </summary>
        int m_NomalHeight = 0;
        /// <summary>
        /// 窗体是否处于悬挂状态
        /// </summary>
        bool m_IsHange = false;

        /// <summary>
        /// 窗体被激活时触发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_Activated(object sender, EventArgs e)
        {
            Text = "Activated:" +MousePosition.ToString();
        }
        /// <summary>
        /// 窗体被停用时触发
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_Deactivate(object sender, EventArgs e)
        {
            Text = "Deactivate:" + MousePosition.ToString();
        }

        /// <summary>
        /// 悬挂
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnHang_Click(object sender, EventArgs e)
        {
            if (this.FormBorderStyle == FormBorderStyle.None)
            {
                this.FormBorderStyle = FormBorderStyle.Sizable;
                pnlHangBar.Visible = false;
            }
            else
            {
                this.FormBorderStyle = FormBorderStyle.None;
                pnlHangBar.Visible = true;
                this.Height = pnlHangBar.Height;
                m_IsHange = true;
            }
        }

        /// <summary>
        /// 窗体位置改变时触发，判断是否应该悬挂窗体
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_LocationChanged(object sender, EventArgs e)
        {
            if (Location.Y <= 0)
            {
                Top = 0;
                m_IsHange = true;
            }
            else
            {
                m_IsHange = false;
            }

            Text = "LocationChanged:" + MousePosition.ToString();
        }

        /// <summary>
        /// 显示或悬挂窗体
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void timer1_Tick(object sender, EventArgs e)
        {
            // 鼠标在屏幕的位置
            lblMousePosition.Text = MousePosition.ToString();
            lblMousePosition2.Text = "鼠标在屏幕的位置：" + MousePosition.ToString();
            // 鼠标在窗体客户端内的位置
            Point pClient = this.PointToClient(MousePosition);
            lblClientPosition.Text = "鼠标在窗体客户端内的位置：" + pClient.ToString();
            // 窗体悬挂
            if (pClient.X < 0 || pClient.X > Width || pClient.Y > Height)  //在窗体客户区域之外时
            {
                if (m_IsHange)
                {
                    this.FormBorderStyle = FormBorderStyle.None;
                    pnlHangBar.Visible = true;
                    this.Height = pnlHangBar.Height;
                }
            }
            else //在窗体客户区域之内
            {
                if (m_IsHange)
                {
                    this.FormBorderStyle = FormBorderStyle.Sizable;
                    pnlHangBar.Visible = false;
                    this.Height = m_NomalHeight;
                }
            }
        }

        private void Form1_Resize(object sender, EventArgs e)
        {
            if(!m_IsHange)
                m_NomalHeight = this.Height;
        }
    }
}

                          

二、单独窗口悬挂

本来不想考虑第二种方式的，但是后来发现需要悬挂的窗口设置高度居然无效，是一个从DevComponents.DotNetBar.Office2007RibbonForm继承的窗口类。

 实现思路基本一样，只是需要注意的是判断当前鼠标的位置需要分不同的窗口转换坐标，还有其他细节见代码。

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

namespace Demo
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
            timer1.Enabled = true;
            timer1.Interval = 500;
        }

        /// <summary>
        /// 窗体是否处于悬挂状态
        /// </summary>
        bool m_IsHange = false;
        /// <summary>
        /// 悬挂标志窗口
        /// </summary>
        FrmHideFlagForm m_HideFlagForm = new FrmHideFlagForm();

        /// <summary>
        /// 窗体位置改变时触发，判断是否应该悬挂窗体
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form2_LocationChanged(object sender, EventArgs e)
        {
            if (Location.Y < 0)
            {
                Top = 0;
                m_IsHange = true;
            }
            else
            {
                m_IsHange = false;
            }
            SetHideFlagFormPos(); 
        }

        /// <summary> 
        /// 设置标志窗体的位置和大小 
        /// </summary> 
        private void SetHideFlagFormPos()
        {
            m_HideFlagForm.Left = this.Left;
            m_HideFlagForm.Top = this.Top;
            m_HideFlagForm.Width = this.Width;
            m_HideFlagForm.Height = 10;
        }

        /// <summary> 
        /// 显示或悬挂窗体
        /// </summary> 
        /// <param name="sender"></param> 
        /// <param name="e"></param> 
        private void timer1_Tick(object sender, EventArgs e)
        {
            if (System.Windows.Forms.Control.MouseButtons == MouseButtons.Left)
                return;  //在鼠标左键为按下时，认为窗口处在拖动状态，暂停鼠标位置的判断 
            ShowHideForm();
        }
        /// <summary> 
        /// 悬挂或者展开窗体 
        /// </summary> 
        private void ShowHideForm()
        {
            Point pMousePosition = new Point(System.Windows.Forms.Control.MousePosition.X,
                System.Windows.Forms.Control.MousePosition.Y);
            Point pClientPosition = new Point();
            int iHight = 0;
            if (this.Visible)
            {
                pClientPosition = PointToClient(pMousePosition);
                iHight = Height;
            }
            else
            {
                pClientPosition = m_HideFlagForm.PointToClient(pMousePosition);
                iHight = m_HideFlagForm.Height;
            }

            if (pClientPosition.X < 0 || pClientPosition.X > Width || pClientPosition.Y > iHight)  //在窗体客户区域之外时 
            {
                if (m_IsHange && FormBorderStyle != FormBorderStyle.None)
                {
                    FormBorderStyle = FormBorderStyle.None;
                    this.Hide();
                    m_HideFlagForm.Show();
                    SetHideFlagFormPos();
                }
            }
            else //在窗体客户区域之内 
            {
                if (m_IsHange && FormBorderStyle != FormBorderStyle.Sizable)
                {
                    FormBorderStyle = FormBorderStyle.Sizable;
                    m_HideFlagForm.Hide();
                    this.Show();
                }
            }
        }

        /// <summary> 
        /// 窗口大小改变事件 
        /// </summary> 
        /// <param name="sender"></param> 
        /// <param name="e"></param> 
        private void Form2_Resize(object sender, EventArgs e)
        {
            m_HideFlagForm.Left = Left;
            m_HideFlagForm.Width = Width;
        }
    }
}

  　　　　　　　　

参考自：http://www.cnblogs.com/haiyabtx/archive/2012/09/21/2697202.html