title: menuitem wont work for ischecked property
body: <p>i have a menuitem to which i have included ischecked property. when a menu item is clicked it should keep on saving files and when menu item is not clicked it should overwrite the previous saved file.
  clicking part is working but when it is not clicked it doesnt overwrite. The value of menuitem remains true all the times.</p>
  <p>.xaml</p>
  <pre><code> &lt;MenuItem Header=&quot;Save&quot; IsChecked=&quot;{Binding Saving ,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}&quot;  &gt;
    
  </code></pre>
  <p>.cs</p>
  <pre><code> private bool saving =true;
      public bool Saving
      {
          get
          {
              return saving;
          }
          set
          {
              saving = value;
              RaisePropertyChanged(&quot;Saving&quot;);
          }
      }
  
   Configuration.isPrevSave = Saving;
  
   if (Configuration.isPrevSave == false &amp;&amp; Configuration.PreviousFilePath != null &amp;&amp; Directory.Exists(Configuration.PreviousFilePath))
                  DirectoryInfo.DeleteContents(Configuration.PreviousFilePath);
              else //works
         
  </code></pre>