private void ShowFormMain()
 {
     try
     {
         if (FormBuildLicense != null)
         {
             FormBuildLicense.Visible = true;
         }
         else
         {
             FormBuildLicense         = new BuildLicense_Form();
             FormBuildLicense.Closed += FormBuildLicense_Closed;
             AddOwnedForm(FormBuildLicense);
             FormBuildLicense.MdiParent = this;
             FormBuildLicense.Show();
         }
     }
     catch (Exception ex)
     {
         LogError.WriteLogError("ShowFormMain", ex);
         MessageBox.Show("Lỗi show form");
     }
 }
 private void FormBuildLicense_Closed(object sender, EventArgs e)
 {
     FormBuildLicense.Dispose();
     FormBuildLicense = null;
 }