title: Convert and Convertback between double and "+" & " -" String
body: <p>I would like to create WPF converter that converts double number to "+" or "-" String based on the number  Sign(positive or negative)
  but I can't handle the converted back method because I don't have the number anymore.
  The "+" and "-" signs bounded to a combobox at the xaml side
  any ideas???</p>
  
  <pre><code>    public class AmountToDebitCreditConverter : IValueConverter
  {
      public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
      {
          if ((value == null) || (System.Convert.ToDecimal(value) == 0))
              return string.Empty;
  
          return System.Convert.ToDecimal(value) &gt; 0 ? "+" : "-";
      }
  
  
      public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
      {
          KeyValue kv = value as KeyValue;
  
          if ((String)value == "+")
              return 1;
          else
              return -1;
      }
  }
  </code></pre>
  
  <p>Here's my Xaml code</p>
  
  <pre><code>    &lt;igDP:UnboundField Name="ActualAdjustmentAmount" Label="PlusMinusKey"  Converter={StaticResource signConverter} &gt;
                              &lt;igDP:Field.Settings&gt;
                                  &lt;igDP:FieldSettings EditorType="{x:Type igEditors:XamComboEditor}"  LabelWidth="40" CellWidth="40"&gt;
                                      &lt;igDP:FieldSettings.EditorStyle&gt;
                                          &lt;Style TargetType="{x:Type igEditors:XamComboEditor}"&gt;
                                              &lt;Setter Property="ItemsSource" Value="{Binding Path=Flags, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}" /&gt;
                                              &lt;Setter Property="FlowDirection" Value="LeftToRight"/&gt;
                                              &lt;Setter Property="SelectedItem" Value="{Binding Path=ActualAdjustmentAmount }" /&gt;
                                          &lt;/Style&gt;
                                      &lt;/igDP:FieldSettings.EditorStyle&gt;
                                  &lt;/igDP:FieldSettings&gt;
                              &lt;/igDP:Field.Settings&gt;
                          &lt;/igDP:UnboundField&gt;
  </code></pre>