private void CategoryCodeTextBox_Validating(object sender, CancelEventArgs e)
 {
     if (string.IsNullOrWhiteSpace(CategoryCodeTextBox.Text))
     {
         e.Cancel = true;
         CategoryCodeTextBox.Focus();
         CategoryCodeTextBoxErrorProvider.SetError(CategoryCodeTextBox, "Field is mandatory!");
     }
     else if (CategoryCodeTextBox.Text.Length > 10)
     {
         e.Cancel = true;
         CategoryCodeTextBox.Focus();
         CategoryCodeTextBoxErrorProvider.SetError(CategoryCodeTextBox, "Code has a maximum length of 10 characters!");
     }
     else
     {
         e.Cancel = false;
         CategoryCodeTextBoxErrorProvider.SetError(CategoryCodeTextBox, "");
     }
 }
 private void AddEditConferenceCategoryScreen_Activated(object sender, EventArgs e)
 {
     CategoryNameTextBoxErrorProvider.SetError(CategoryNameTextBox, "");
     CategoryCodeTextBoxErrorProvider.SetError(CategoryCodeTextBox, "");
 }