WPF

1. Dropdown is combobox.
  <ComboBox SelectedIndex="0" Padding="2">
                <ComboBoxItem>Painted</ComboBoxItem>
                <ComboBoxItem>Not Painted</ComboBoxItem>

            </ComboBox>
  2.    In case of Text Box name attribute is used so that we get its text user name attribut .get Text in code
  <TextBox Name="description_box" />

3. for checking string null check in code use
        string desc =description_box.Text
        String.IsNullOrEmpty(desc)
        
        
        https://www.youtube.com/watch?v=gTFobW68uoI