title: How to style Group Headers of RadDataForm?
body: <p><a href="https://docs.nativescript.org/ui/components/DataForm/dataform-styling#styling-group-headers" rel="nofollow noreferrer">DataForm docs</a> says; I  need to create an instance of <em>GroupTitleStyle</em> and set it to the <em>PropertyGroup</em>'s <em>titleStyle</em> property.</p>
  <h2>But how and where to create <code>grouptitlestyle</code>  in nativescript-vue?</h2>
  <p>I have created an <a href="https://play.nativescript.org/?template=play-vue&amp;id=rqK7wO&amp;v=8" rel="nofollow noreferrer">{N} playground</a></p>
  <p>I already tried:</p>
  <pre class="lang-js prettyprint-override"><code>         return {
               groups: [
                      Object.assign(new PropertyGroup(), {
                          name: &quot;Personal&quot;,
                          collapsible: true,
                          collapsed: false,
                          titleStyle: {
                              labelTextSize: 22
                          }
                      }),
  
                      Object.assign(new PropertyGroup(), {
                          name: &quot;Address&quot;,
                          collapsible: true,
                          collapsed: true
                      })
                  ],
  
  </code></pre>
  <p>Would you please help me to <strong>set</strong> <code>labelTextSize</code> to RadDataForm <strong>groups</strong>?</p>
  <p>Thanks in advance</p>