title: Showing/Closing forms in wpf
body: <p>Im developing an application using wpf template I have these 2 windows:
  MainWindow.xaml and
  JungleTimer.vb which is a Windows Form</p>
  
  <p>I have a button in my main windows which shows JungleTimer form using this code:</p>
  
  <pre><code>Dim JungleTimer As New JungleTimer
          JungleTimer.Show()
  </code></pre>
  
  <p>But as you see, clicking this button multiple times will show multiple JungleTime form.
  I tried to use this code to check if JungleTimer is visible but it doesn't work:</p>
  
  <pre><code>Dim JungleTimer As New JungleTimer
          If JungleTimer.Visible = False Then
              JungleTimer.Show()
          End If
  </code></pre>
  
  <p>I also need the code to close the JungleTimer form.</p>