title: QTableView not resizing when resizing main window
body: <p>I've got a GUI in PyQt that does the following:
  The main window is a grid layout (2 columns and 3 rows). This is the scheme (soory I can't post images yet):
  <a href="https://i.stack.imgur.com/0vLln.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0vLln.png" alt="PicOne"></a></p>
  
  <p>Now, when resizing the Main Window I'd like the <a href="http://doc.qt.io/qt-5/qtableview.html#details" rel="nofollow noreferrer">QTableView</a> widgets to be resized. However, it happens otherwise:
  <a href="https://i.stack.imgur.com/RV007.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RV007.png" alt="PicTwo"></a>
  And the tables stay almost fixed in size (but every size-fixing property is set not to fix anything), they just expand for about 50 píxels. I've tried changing the main layout to a horizontal layout and then putting vertical layouts there but no change. I'm designing the GUI with the <code>QtDesigner</code> as I have no clue on how to doing it by hand-writing the code, and I need to export it to python.</p>
  
  <p>What's the property determining which layout gets expanded and which one not?</p>