>>>This.MaxLength = ;
>>> iif(!empty[This.ControlSource], fsize[This.ControlSource], 0)
>>>Anyone have any luck with this?
>That is what I am doing, but when I try it, the length seems to be font-specific (I am using Aerial). For example, for a 40 character field, it does not terminate until about character 46.

Mark,

Well I would tend to use LEN() instead of fsize() becasue fsize is for fields only and the controlsource might be a non-field. I also would use an InputMask of REPLICATE("X",LEN(THIS.Controlsource))instead of the Maxlength, only becasue that is how I've done it before and it works.