MFC工具提示控件（ctooltipctrl）是易于使用的一个窗口，如一个孩子…

代码说明：

MFC Tool tip control(CToolTipCtrl) is easy to use with a window, such as a child window, or an application-defined rectangular area within a window s client area. However, in some situations you may not know in advance for which controls or rectangle area you will be displaying the tool tip. In this case, you have to dynamically display the tool tip depending on where your mouse position is. For e.g. you may have a window which display some graphics and you may want to display the tool tip on the graphics depending on where the mouse position is.