protected void gvStudents_RowDataBound(object sender, GridViewRowEventArgs e)
 {
     if (e == null)
     {
         throw new ArgumentNullException(nameof(e));
     }
     // Show link to view logbook IF can view student's book
     // set the checkbox to set the permission to view the logbook
     if (e.Row.RowType == DataControlRowType.DataRow)
     {
         // Get a list of pending un-signed flights for this student
         GridView gvPendingFlightsToSign = (GridView)e.Row.FindControl("gvPendingFlightsToSign");
         gvPendingFlightsToSign.DataSource = LogbookEntry.PendingSignaturesForStudent(m_pf, (InstructorStudent)e.Row.DataItem);
         gvPendingFlightsToSign.DataBind();
     }
 }
 protected void RefreshFlightsToBeSigned()
 {
     gvFlightsAwaitingSignatures.DataSource = LogbookEntry.PendingSignaturesForStudent(null, m_pf);
     gvFlightsAwaitingSignatures.DataBind();
 }