Ribbon Toggle Button state

private void ExecuteBoldCommand(object sender, ExecutedRoutedEventArgs e)
        {
            // This happens after the mouse up event and the button always has 
            // an unchecked state when this code executes.  Subsequent 
            // CanExecuteBoldCommand will set state to checked (if it should be) 
            // causing the flickering.
            DoBoldExecute();
        }

        private void CanExecuteBoldCommand(object sender, CanExecuteRoutedEventArgs e)
        {
            CheckableCommandParameter checkableParameter = e.Parameter as CheckableCommandParameter;

            if (checkableParameter != null)
            {
                if (_style != null)
                {
                    checkableParameter.IsChecked = IsFontStyleOn(StyleProperties.Bold);
                }
                else
                {
                    checkableParameter.IsChecked = false;
                }
                checkableParameter.Handled = true;
            }

            if (_style == null)
            {
                e.CanExecute = false;
            }
            else
            {
                e.CanExecute = ExecutionUtility.CanExecuteBoldCommand();
            }
        }