title: qt designer how to select multiple children of a QStackedWidget page?
body: <p>In qt designer, I have placed a QStackedWidget with 2 pages inside QMainWindow. And there are many widgets inside the first page as shown below:
  <a href="https://i.stack.imgur.com/QKpm8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QKpm8.png" alt="enter image description here"></a></p>
  
  <p><strong>Now, I want to select all widgets inside the red box area. How to do that easily?</strong></p>
  
  <p>It seems I can not select multiple widgets by selecting a rectangle area with my mouse.</p>
  
  <p><strong>Update:
  I know I can press CTRL and click all widgets I want one by one. But it seems time consuming when there are hundreds of widgets which is possible in my app.</strong></p>