这是一本学习 window编程的很好的参考教材

				// PopupTipWnd.cpp : implementation file
				//
				
				#include "stdafx.h"
				#include "PwdSpy.h"
				#include "PopupTipWnd.h"
				
				#ifdef _DEBUG
				#define new DEBUG_NEW
				#undef THIS_FILE
				static char THIS_FILE[] = __FILE__;
				#endif
				
				// Register control during class initialization
				bool CPopupTipWnd::s_bRegistered = CPopupTipWnd::RegisterWindowClass();
				
				/////////////////////////////////////////////////////////////////////////////
				// CPopupTipWnd
				
				CPopupTipWnd::CPopupTipWnd()
				{
					m_pParentWnd = NULL;
				}
				
				CPopupTipWnd::~CPopupTipWnd()
				{
				}
				
				BEGIN_MESSAGE_MAP(CPopupTipWnd, CWnd)
					//{{AFX_MSG_MAP(CPopupTipWnd)
					//}}AFX_MSG_MAP
				END_MESSAGE_MAP()
				
				/////////////////////////////////////////////////////////////////////////////
				// CPopupTipWnd message handlers
				
				//***********************************************
				BOOL CPopupTipWnd::Create(CWnd *pParentWnd)
				{
					_ASSERTE(pParentWnd);
				
					m_pParentWnd = pParentWnd;
				
					DWORD dwStyle = WS_BORDER | WS_POPUP;
					DWORD dwExStyle = WS_EX_TOOLWINDOW | WS_EX_TOPMOST;
				
					BOOL bCreated = CreateEx(dwExStyle,
						PWDSPY_POPUP_TIP_CLASSNAME,
						NULL,
						dwStyle,
						0, 0, 0, 0,
						NULL, NULL, NULL);
				
					return bCreated;
				}
				
				//***********************************************
				bool CPopupTipWnd::RegisterWindowClass(void)
				{
					WNDCLASS wndcls = {0};
					wndcls.style = CS_SAVEBITS | CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW;
					wndcls.lpfnWndProc = ::DefWindowProc;
					wndcls.hCursor = (HCURSOR)::LoadImage(NULL, IDC_ARROW, IMAGE_CURSOR, 0, 0, LR_DEFAULTSIZE);
					wndcls.hbrBackground = (HBRUSH)(COLOR_INFOBK + 1);
					wndcls.lpszClassName = PWDSPY_POPUP_TIP_CLASSNAME;
				
					if(!::RegisterClass(&wndcls))
					{
						AfxThrowResourceException();
						return false;
					}
				
					return true;
				}
				
				//***********************************************
				void CPopupTipWnd::ShowPopupWindow(CString strText, CPoint point, CRect rect)
				{
					// If there is no password, instead hide the window and be done with it
					if(strText.IsEmpty())
					{
						HidePopupWindow();
						return;
					}
				
					CClientDC dc(this);
				
					// Use same font as parent window
					CFont *pOldFont = dc.SelectObject(m_pParentWnd->GetFont());
				
					// Calculate the window size.
					CSize sizeText = dc.GetTextExtent(strText);
					CSize sizeWindow;
					sizeWindow.cx = sizeText.cx + 2 * BORDER_X;
					sizeWindow.cy = sizeText.cy + 2 * BORDER_Y;
				
					// Draw information in window
					dc.SetBkMode(TRANSPARENT);
					dc.DrawText(strText, CRect(0, 0, sizeWindow.cx, sizeWindow.cy), DT_CENTER | DT_VCENTER | DT_SINGLELINE);
					dc.SelectObject(pOldFont);
				
					// Calculate window rectangle position on screen
					CRect rectWindow;
					rectWindow.left = rect.left;
					rectWindow.right = rectWindow.left + sizeWindow.cx;
					rectWindow.top = rect.top - (sizeWindow.cy + 20);
					if(rectWindow.top 						rectWindow.top = rect.bottom + 20;
					rectWindow.bottom = rectWindow.top + sizeWindow.cy;
				
					// Display window
					SetWindowPos(&wndTop,
						rectWindow.left,
						rectWindow.top,
						rectWindow.Width(),
						rectWindow.Height(),
						SWP_SHOWWINDOW | SWP_NOACTIVATE);
				}
				
				//***********************************************
				void CPopupTipWnd::HidePopupWindow(void)
				{
					ShowWindow(SW_HIDE);
				}