title: Flutter: How to display Tooltip for TextSpan inside RichText
body: <p>I have big paragraph, and many words have to have tooltip message. When you click on any of these words, then tooltip message should be appeared.</p>
  <p>I tried to use RichText widget where it contains many <code>TextSpan</code> children like below:</p>
  <pre><code>RichText(
    text: TextSpan(
       children: &lt;TextSpan&gt;[
          TextSpan(text: &quot;Welcome to&quot;),
          TextSpan(text: &quot;Flutter&quot;),
          ... 
       ]),
  ),
  </code></pre>
  <p>I need to display tooltip text when i click on <code>TextSpan</code>
  I tried to wrap <code>TextSpan</code> with <code>Tooltip</code> widget</p>
  <pre><code>RichText(
    text: TextSpan(
       children: &lt;TextSpan&gt;[
          TextSpan(text: &quot;Welcome to&quot;),
          ...
          Tooltip(
              message: &quot;any text here&quot;,
              child: TextSpan(text: &quot;Flutter&quot;),
          ),
          ...            
       ]),
  ),
  </code></pre>
  <p>but this is not possible since the children have to be <code>TextSpan</code> only.</p>
  <p>anyone have an idea on how to achieve this requirement?</p>