title: Binding with or condition
body: <p>i have two <code>check boxes</code> and a <code>text box</code>. the text box's <code>IsEnabled</code> property should be binded to both of those check box's <code>IsChecked</code> Properties. if one of check box or both of them are enabled then text box should be enabled.
  the first solution that came to my mind was <code>multibinding</code>. But it needs another class to do. Is there any easier way to do this?</p>