private void ApplicationUndoCommand_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     if (lstHistory == null || lstHistory.Items.Count == 0)
         e.CanExecute = false;
     else
         e.CanExecute = true;
 }

 private void Refresh_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     if (_pageLoaded)
     {
         e.CanExecute = true;
     }
 }

		private void CanExecuteAddControlCommand(object sender, CanExecuteRoutedEventArgs e)
		{
			//var type = GetType(e.Parameter);

			//e.CanExecute = type == null || _controls.All(c => c.Control.GetType() != type.Item1);
			e.CanExecute = true;
		}

 private void pausethejob_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     var j = this.DataContext as Job;
       if (j != null && j.IsProcessing) {
     e.CanExecute = true;
       }
 }

        private static void CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            FrameworkElement senderElement = (sender as FrameworkElement);

            if (HelpProvider.GetHelpString(senderElement) != null)
                e.CanExecute = true;
        }

 void canExecute_Save(object sender, CanExecuteRoutedEventArgs e)
 {
     if (Surname.Text != "" && Name.Text != "" && Patronymic.Text != "" && Year.Text != "" && Male.Text != "") 
         e.CanExecute = true; 
     else 
         e.CanExecute = false;
 }

 private static void CanExecuteSave(object sender, CanExecuteRoutedEventArgs e)
 {
     if (sender == null)
         throw new ArgumentNullException("sender");
     var owner = sender as Example;
     e.CanExecute = owner != null && owner.diagram != null && owner.diagram.Items.Count > 0;
 }

 private void CommandClearTrace_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     if (!string.IsNullOrEmpty(txtTrace.Text))
     {
         e.CanExecute = true;
     }
 }

 private void ResetDecoder_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     //e.CanExecute =
     //    station != null && station.Connected && Decoder != null &&
     //    ((station.MainTrackActive && (NMRAProgramMode)cbProgramMode.SelectedValue == NMRAProgramMode.POM) || (NMRAProgramMode)cbProgramMode.SelectedValue != NMRAProgramMode.POM)
     //    ;
 }

 private void CommandBinding_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     if (e.Command.Equals(ApplicationCommands.Find))
     {
         e.CanExecute = !this.IsUpdateChecking;
     }
 }

        /// <summary>
        /// Determine if the start button should be enabled
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void StartGame_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            var playerSetupControls = StackPanel_Players.Children.OfType<PlayerSetup>();
            List<string> usedNames = new List<string>(5);
            foreach (var playerSetupControl in playerSetupControls)
            {
                if (playerSetupControl.IsRequired && playerSetupControl.IsEmpty)
                {
                    e.CanExecute = false;
                    e.Handled = true;
                    return;
                }
                else if (playerSetupControl.IsEmpty == false)
                {
                    if (usedNames.Contains(playerSetupControl.PlayerName.ToUpper()))
                    {
                        e.CanExecute = false;
                        e.Handled = true;
                        return;
                    }
                    usedNames.Add(playerSetupControl.PlayerName.ToUpper());
                }
            }

            e.CanExecute = true;
            e.Handled = true;
        }

        private void Command_CanExecute_MoveInHistory(object sender, CanExecuteRoutedEventArgs args)
        {
            if (args.Parameter == null) return;

            if (int.Parse(args.Parameter.ToString()) == -1)
            {
                if (lbHistory.SelectedIndex == 0 || lbHistory.SelectedIndex == -1)
                {
                    args.CanExecute = false;
                }
                else
                {
                    args.CanExecute = true;
                }
            }
            else
            {
                if (lbHistory.SelectedIndex == lbHistory.Items.Count - 1)
                {
                    args.CanExecute = false;
                }
                else
                {
                    args.CanExecute = true;
                }
            }
        }

 private void gl_editCmd_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     if (this.xCatNameTxt.Text == "")
         e.CanExecute = false;
     else
         e.CanExecute = true;
 }

 private void CreateLinkFromSelectionCanExecute(object sender, CanExecuteRoutedEventArgs args)
 {
     RichTextBox wikiEditor = sender as RichTextBox;
     args.CanExecute = !wikiEditor.Selection.IsEmpty;
     args.ContinueRouting = false;
     args.Handled = true;
 }

		private void ClearOutputCommand_CanExecute(object sender, CanExecuteRoutedEventArgs e)
		{
			if (Model == null)
				return;

			e.CanExecute = Model.ExecutedScripts.Any();
		}

 private void SwitchToIdleModeCommand_CanExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     if (VM.InputMode == Controls.Problem.InputMode.Idle)
         e.CanExecute = false;
     else
         e.CanExecute = true;
 }

 private void CanExecuteOpenComponentGraphCommand(object sender, CanExecuteRoutedEventArgs e)
 {
     if (OpenComponentGraphCommand != null)
     {
         e.CanExecute = OpenComponentGraphCommand.CanExecute(e.Parameter);
     }
 }

 private void OpenInBrowser_CanExecute(object sender, CanExecuteRoutedEventArgs e) {
     var url = (string)e.Parameter;
     Uri uri;
     e.CanExecute = Uri.TryCreate(url, UriKind.Absolute, out uri) &&
                    (uri.Scheme == Uri.UriSchemeHttp || uri.Scheme == Uri.UriSchemeHttps);
     e.Handled = true;
 }

        void PrintCommandBinding_CanExecute(object sender, CanExecuteRoutedEventArgs e)
        {

            if (MySQLHandler.ClassList.Default.Dt.Rows.Count == 0)
                e.CanExecute = false;
            else e.CanExecute = true;
        }

 private void CanAddBookItemExecute(object sender, CanExecuteRoutedEventArgs e)
 {
     e.CanExecute = !String.IsNullOrWhiteSpace(uxAddBookTitle.Text) &&
                    !String.IsNullOrWhiteSpace(uxAddBookAuthor.Text);
     //&& !String.IsNullOrWhiteSpace(uxAddBookISBN.Text);
     e.Handled = true;
 }