title: Combobox show and hide ComboBox items in WPF
body: <p>ComboBox might have a lot of items.</p>
  
  <p>This is the scenario i would like to achieve:</p>
  
  <p>I have to create a custom <code>ComboBox</code> which has a "More" button which located at the last of the <code>ComboBox</code> items. If the <code>ComboBox</code> contain of 20 items, initially, when the <code>ComboBox</code> is clicked and the drop down list is shown, there are only 10 items and a "More" button under the 10th items are displayed.</p>
  
  <p>Whenever the "More" button items is clicked, the "More" button will turn into "Less" and the drop down list will display total of 20 items. So when "Less" button is clicked, the display items will be reversed back to 10 items and the another 10 items will be hidden.</p>
  
  <p>The 10 initial display items is just an example. Actually, The total of the <code>ComboBox's</code> initial display item can be set through the property. </p>
  
  <p>For example:  <code>&lt;local:CustomComboBox x:Name="CustomComboBox" InitialDisplayItem="10" /&gt;</code></p>
  
  <p>I am new to wpf...How can i achieve that?</p>