Adding multiline balloon tooltips to ListView column headers (updated)

The code uses subclassing technique to trap the WM_MOUSEMOVE event of the Header control which is a constituent part of the ListView control. The handler for this event determines the index of the column header under the mouse pointer and changes the tooltip text respectively; it uses the HDM_HITTEST message for this purpose. To find the handle of the Header control inside ListView from MSCOMCTL.OCX, the code uses the FindWindowEx function which searches for the child window with the "msvb_lib_header" class inside the ListView control.