procedure TForm1.RichEdit1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
var
a:integer;
begin
a:=RichEdit1.Perform(EM_LINELENGTH,RichEdit1.SelStart,0);
RichEdit1.SelStart:=RichEdit1.Perform(EM_LINEINDEX,RichEdit1.CaretPos.Y,0);
RichEdit1.SelLength:=a;
end;
end.