title: Move splitters in design mode
body: <p>When i add splitters, it acts as a layout, but also allows to resize the widgets <em>in runtime</em>. So, for example, i managed to lay out my widgets in this way:</p>
  
  <p><a href="https://i.stack.imgur.com/W4NGo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/W4NGo.png" alt="enter image description here"></a></p>
  
  <p>Therefore, i can resize my widgets in runtime. As i noticed, this function is also available in designer mode, but it doesn't work properly. I tried to hover over my splitter and drag it in designer mode, but it only replaces the entire widget.</p>
  
  <p><a href="https://i.stack.imgur.com/SdjYH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SdjYH.png" alt="enter image description here"></a></p>
  
  <p>That is how does my main window look like in QtDesigner. I haven't tried to code yet. The problem is, that even though i used to set a stretch factor, my widegt's look in designer mode and in runtime completely differ. <strong>They have another sizes</strong>.</p>
  
  <p>So, what are the problems:</p>
  
  <ul>
  <li><strong>Firstly</strong>, i can't change my widgets sizes properly, using stretch factors. I don't know, i tried to change size policies, but i did't manage to see an effect. I have somehow changed size of the vertically oriented widgets, but when speak about horizontal orientation - stretch factor and size policy doesn't change anything at all.</li>
  <li><strong>Secondly</strong>, i can't move my splitter in designer mode. It's position is constant, by default, it's always somewhere in the middle.</li>
  <li><strong>Thirdly</strong>, i have bugs (i think so) with my widget sizes in designer mode. They differ with widget's sizes in runtime.</li>
  </ul>
  
  <p><strong>Question:</strong>
  So, how can i change widget's sizes properly? Maybe there's a way of <strong>moving a splitter in designer mode</strong> - do newer versions of Qt have it? Currently i'm using Qt 5.9.9.  Also, why these bugs, and are they bugs at all. Maybe i just should update my Qt to newer versions to get access to newer functionalities?</p>
  
  <p><em>Comment:</em> I'm not sure if stretch factors work with layout as they do with widgets. I'm using layouts exactly the same way i use widgets. My layout's wrong(maybe) use may have caused this problem. Anyways, i'm entirely new to Qt, and may not know something to understand it completely.</p>