title: Validation textbox WPF
body: <p>How can i add validation to a textbox that isnt bound ...</p>
  
  <pre><code> &lt;TextBox BorderThickness="1" Grid.Column="1" HorizontalAlignment="Stretch" Margin="3" x:Name="txtbFirstName" VerticalAlignment="Center" &gt;
                              &lt;TextBox.Text&gt;
                                  &lt;Binding  &gt;
                                      &lt;Binding.ValidationRules&gt;
                                          &lt;local:validator Max="999.99" /&gt;
                                      &lt;/Binding.ValidationRules&gt;
                                  &lt;/Binding&gt;
                              &lt;/TextBox.Text&gt;
                          &lt;/TextBox&gt;
  </code></pre>
  
  <p>doenst work</p>