procedure TForm1.ListView1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
var
r : TRect;
aItem: TListItem;
begin
aItem := ListView1.GetItemAt(X,Y);
if (aItem = nil) then Exit;
r:=aItem.DisplayRect(drBounds);
r.Right :=aItem.DisplayRect(drLabel).Left;
if (X >r.Left) and (X <r.Right) and (Y>R.Top) and (Y<R.Bottom) then begin
//鼠标在checkbox点击