Just assign the next code to the OnMouseMove event handler for the ListBox (ListBox1) component.
~~~~~~~~~~~~~~~~~~~~~~~~~
procedure TForm1.ListBox1MouseMove
(Sender: TObject; Shift: TShiftState; X, Y: Integer) ;
begin
ListBox1.ItemIndex := ListBox1.ItemAtPos(Point(x,y), True) ;
end;
~~~~~~~~~~~~~~~~~~~~~~~~~
Delphi tips navigator:
» What's the word under the mouse cursor in a TRichEdit?
« Enable or disable a control by name

