title: Items set to Visible=false are being shown when tabbing inside TabControl
body: <p>So I am making a new project and I am using a theme for the first time (MetroSet). I currently have 30 buttons in a <code>MetroSetTabControl</code> tab all set to Visible=false. When I first launch the application, all is good. If I tab over to the 2nd tab, then go back to the first, all buttons are now shown. </p>
  
  <p>Any ideas why its doing this, or how to resolve?</p>
  
  <p>See GIF below</p>
  
  <p><a href="https://i.stack.imgur.com/SAxtN.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SAxtN.gif" alt="GIF added to show what I am talking about"></a></p>
  
  <p><strong>Theme Set Being used:</strong> <a href="https://github.com/N-a-r-w-i-n/MetroSet-UI" rel="nofollow noreferrer">https://github.com/N-a-r-w-i-n/MetroSet-UI</a></p>
  
  <p><strong>Steps to replicate:</strong> </p>
  
  <ol>
  <li><p>Create a new Windows Forms Application project in Visual Studio and install <a href="https://www.nuget.org/packages/MetroSet_UI/" rel="nofollow noreferrer">MetroSet_UI</a> via nuget:</p>
  
  <pre><code>Install-Package MetroSet_UI
  </code></pre></li>
  <li><p>Create a <a href="https://github.com/N-a-r-w-i-n/MetroSet-UI/blob/master/MetroSet%20UI/Forms/MetroSetForm.cs" rel="nofollow noreferrer"><code>MetroSetForm</code></a> and insert a <a href="https://github.com/N-a-r-w-i-n/MetroSet-UI/blob/master/MetroSet%20UI/Controls/MetroSetTabControl.cs" rel="nofollow noreferrer"><code>MetroSetTabControl</code></a> with 2 tabs</p></li>
  <li>Add 1 or more <a href="https://github.com/N-a-r-w-i-n/MetroSet-UI/blob/master/MetroSet%20UI/Controls/MetroSetButton.cs" rel="nofollow noreferrer"><code>MetroSetButton</code></a> to index 0 and set them all to <code>Visible=false</code>. </li>
  <li>Debug application starting on index 0</li>
  <li>Toggle to index 1 and back to 0</li>
  </ol>