Problem edit boxes and text boxes

I have a problem with behaviour of some edit boxes and text boxes in a
form.
I'm using Visual FoxPro 9.
I created the form using the form design wizard. This form has a few edit
boxes and text boxes, buttons etc.
The values for text foxes are assign like this thisform.t1.value=hs.text
hs.text is a field from a free table. I can type text in t1 text box but
when I click the mouse and move it to one of the sides of the text box the
contents scroll to the opposite direction and become invisible!
If I resize the height of the textbox to twice the height it should have
to display the text the scrolling stops ant the text box acts a it should.
I've used ms access before and when you create a text box or edit box this
does not happen.
I've tried using max InputMask and MaxLenght to control this but the same
thing happens.
What I want, in this case, is a text box that can accept 6 alphanumeric
characters, centred.
Any one was an idea of what I could be doing wrong?

Thanks in advance.