The TCM_SETTOOLTIPS message assigns a tooltip control to a tab control. You can send this message explicitly or by using the TabCtrl_SetToolTips macro.
TCM_SETTOOLTIPS wParam = (WPARAM) (HWND) hwndTT; // handle to the tooltip control lParam = 0; // not used; must be zero
No return value.
You can get the tooltip control associated with a tab control by using the TCM_GETTOOLTIPS message.