i do this in code if you need to do it dynamicly. Try this, i have not tested
this, but it should work. Please let me know.
use the rowediting event to find the text box and then set the width.
Protected Sub GridView1_RowEditing(ByVal sender As Object, ByVal e As
System.Web.UI.WebControls.GridViewEditEventArgs) Handles GridView1.RowEditing
Dim tb As TextBox =
Me.GridView1.Rows(Me.GridView1.SelectedIndex).Cells(3).FindControl("mytextbox")
tb.Width = 75
End Sub
you need to know the cell number and the name of the text box where your
template field is.
Try this