In the keypress, put someting like this:

do case
  case len(trim(this.value))>50
     this.height=48
  case len(trim(this.value))>25
     this.height=32
  otherwise
     this.height=16
endcase

>Dear Sir,
>
>I have a textbox with following properties
>
>hight=16
>width=200
>
>I can write 25 characters in it.
>
>When number of characters increases
>more than 25, the textbox height should be =32,double, and when
>more than 50, the textbox height should be =48,tripple, and so on.
>
>To do this what should I do?
>
>For some reasons I do not want to use Editbox instead of Textbox.
>
>Please help