>Albert,
>
> I've just tried. It's not convenient to append 0 to the end, because cursor goes automatically to the next line. Say, I type 1, then I see 1000 with cursor on another line.

So, don't append zeroes. I left it up to you to manage the caret.

>
> I also don't like to define class in a program. I always use class designer instead. I understand, that sometimes it's only way to define class in a program, but I prefer to do it visually.

Is it so hard to cut and paste into the class designer?

The important lesson to learn is the way I used delegation to hang on customizable behavior onto the control.