Enabling Tool Tips
You can enable tool tip support for the child controls of a window (such as the controls on a form view or dialog box).
To enable tool tips for the child controls of a window
Call EnableToolTips for the window for which you want to provide tool tips.
Provide a string for each control in your TTN_NEEDTEXT notification handler. The handler is in the message map of the window that contains the child controls (for example, your form view class). This handler should call a function that identifies the control and sets pszText to specify the text used by the tool tip control.