# C1.WPF.C1TreeViewItem.OnExpandButtonClick

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<h1 id="C1_WPF_C1TreeViewItem_OnExpandButtonClick_" data-uid="C1.WPF.C1TreeViewItem.OnExpandButtonClick*">OnExpandButtonClick Method
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<h4 id="C1_WPF_C1TreeViewItem_OnExpandButtonClick" data-uid="C1.WPF.C1TreeViewItem.OnExpandButtonClick">OnExpandButtonClick()</h4>
<div class="markdown level1 summary"><p>Called when the user clicks the expand/collapse button.</p>
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<h5 class="declaration">Declaration</h5>
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  <pre><code class="lang-csharp hljs">protected virtual void OnExpandButtonClick()</code></pre>
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  <pre><code class="lang-vbnet hljs">Protected Overridable Sub OnExpandButtonClick()</code></pre>
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