There is only one class-specific style associated with toolbars: TBSTYLE_TOOLTIPS. When you specify this style, the toolbar creates and manages a tooltip control. A tooltip control is a small pop-up window that contains a line of text describing a toolbar button. The tooltip control is hidden and appears only when the user puts the cursor on a toolbar button, leaving it there for approximately one second. The tooltip control is displayed near the cursor.
When the toolbar receives a WM_MOUSEMOVE message, it sends a notification message to the tooltip control. The tooltip control sets a timer, and after approximately one second, checks if the cursor is still at the same location and is on a toolbar button. If it is, the tooltip control sends the TTN_NEEDTEXT notification message to the parent window to retrieve the descriptive text for the button. Then the tooltip control creates a pop-up window and displays the text in the window. The tooltip control destroys the pop-up window when the user clicks a mouse button or moves the cursor out of the toolbar.
An application that needs to send messages directly to the tooltip control can retrieve the handle of the tooltip by using the TB_GETTOOLTIPS message. An application can replace the tooltip control of a toolbar by using the TB_SETTOOLTIPS message. For more information about tooltip controls, see Tooltip Controls.