codice:
Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs)
	Select Case e.Row.RowType
		Case DataControlRowType.DataRow
			Dim imgb As ImageButton = DirectCast(e.Row.Cells(1).Controls(2), ImageButton)
			imgb.Attributes.Add("onclick", "if (!confirm('Sei sicuro di voler cancellare questo record?') ) {return false;}")
	End Select
End Sub
non ho trovato di meglio