showing tooltip on controls (description on TTN_NEEDTEXT)

Before the tool tip is displayed, the TTN_NEEDTEXT notification message is sent to the owner window of the toolbar to retrieve the descriptive text for the button. If the owner window of the toolbaris a CFrameWnd window, tool tips are displayed wihout any extra effort, because CFrameWnd has a default handler for the TTN_NEEDTEXT notification. If the owner window of the toolbaris not derived from CFrameWnd, such as a dialog box or form view, you must add an entry to the message map of your owner window and provide a notification handler in the message map. The entry to the message map of your owner window is as follows:

ON_NOTIFY_EX( TTN_NEEDTEXT, 0, memberFxn )
memberFxn
The method to be called when text is needed for this button.
Note that the id of a tool tip is always 0.

In addition to the TTN_NEEDTEXT notification, a tool tip control can send the following notifications to a toolbar control:

Notification Meaning
TTN_NEEDTEXTA Tool tip control requires ASCII text (Win95 only).
TTN_NEEDTEXTW Tool tip control requires UNICODE text (Windows NT only).
TBN_HOTITEMCHANGE Indicates that the hot (highlighted) item has changed.
NM_RCLICK Indicates the user has right-clicked a button.
TBN_DRAGOUT Indicates the user has clicked the button and dragged the pointer off the button. It allows an application to implement drag and drop from a toolbar button. When receiving this notification, the application will begin the drag and drop operation.
TBN_DROPDOWN Indicates the user has clicked a button that uses the TBSTYLE_DROPDOWN style.
TBN_GETOBJECT Indicates the user moved the pointer over a button ithat uses the TBSTYLE_DROPPABLE style. The message.