panel.xaml

<StackPanel Visibility="Hidden">

  <StackPanel.Style>
      
      <Style>
          
          <Style.Triggers>

              <MultiDataTrigger>

                  <MultiDataTrigger.Conditions>
                      <Condition Binding="{Binding LoggingIn}" Value="False" />
                      <Condition Binding="{Binding LoggedIn}" Value="False" />
                  </MultiDataTrigger.Conditions>

                  <Setter Property="StackPanel.Visibility" Value="Visible" />

              </MultiDataTrigger>

          </Style.Triggers>
          
      </Style>
          
  </StackPanel.Style>