The TCM_GETITEMRECT message retrieves the bounding rectangle for a tab in a tab control. You can send this message explicitly or by using the TabCtrl_GetItemRect macro.
TCM_GETITEMRECT wParam = (WPARAM) (int) iItem; // index of the tab lParam = (LPARAM) (RECT FAR *) prc; // pointer to a structure to receive rectangle of tab
Returns TRUE if successful or FALSE otherwise.