Gridview with multiline edit

[roend83]

I am trying to extend the default gridview control to allow for editing
of multiple rows when a button is clicked and no rows when the button
is clicked again. When the button is clicked, I call the following
method:
public void SetRowsToEditable()
{
foreach (GridViewRow r in Rows)
{
r.RowState = DataControlRowState.Edit
}
}

The problem is the table reloads but doesn't insert textboxes into the
gridview to edit the rows. Is there another method I should call or
property that I need to set in order for this to work?