CToolTipCtrl 사용
The CToolTipCtrl class encapsulates the functionality of a tool tip control, a small pop-up window that displays a single line of text describing the purpose of a tool in an application. A tool tip is hidden most of the time, appearing only when the user puts the cursor on a tool and leaves it there for approximately one-half second. The tool tip appears near the cursor and disappears when the user clicks a mouse button or moves the cursor off of the tool.