title: QML How to show multiple Popup on a window? (for ToolTip)
body: <p>I want to show all ToolTips of buttons when a helper button's clicking triggered.
  I could do it with only a button with ToolTip.show(&quot;Some instruction&quot;, -1), but when I called this method with more than 1 buttons, only last called ToolTip show itself.<br />
  I found the ToolTip inherits Popup, so I think I can solve my problem if I can make multiple Popups to show on a window.
  Below is what I wanted to do. Any ideas?</p>
  <pre><code>Button {
      id: helperButton
      text: &quot;Help&quot;
      onClicked: {
          otherButton1.ToolTip.show(&quot;button 1's instruction&quot;, -1)
          otherButton2.ToolTip.show(&quot;button 2's instruction&quot;, -1)
          otherButton3.ToolTip.show(&quot;button 3's instruction&quot;, -1)
      }
  }
  
  /// Result: Only ToolTip of @otherButton3 shows. I want all buttons' ToolTip show at the same time.
  </code></pre>