title: QGridLayout with PlotWidget-pyqtgraph
body: <p>I have 3 <a href="http://www.pyqtgraph.org/documentation/widgets/plotwidget.html" rel="nofollow noreferrer"><code>PlotWidget</code></a> (from the <code>pyqtgraph</code> library), <code>obj1</code>, <code>obj2</code> and <code>obj3</code>, which I try to insert in a QGridLayout. I want to display all three objects in a single row, but <code>obj1</code> must be twice as large as <code>obj2</code> and <code>obj3</code>.</p>
  
  <p>Thus I wrote:</p>
  
  <pre><code>layout.addWIdget(obj1, 0, 0, 1, 2)
  layout.addWidget(obj2, 0, 2, 1, 1)
  layout.addWidget(obj3, 0, 3, 1, 1)
  </code></pre>
  
  <p>However, visually, <code>obj1</code> is much smaller than <code>obj2</code> and <code>obj3</code> which do have the same size:</p>
  
  <pre><code>---------------------------------------------------
  | obj1 |     obj2           |         obj3         |
  ---------------------------------------------------
  </code></pre>
  
  <p>However, if I write:</p>
  
  <pre><code>layout.addWIdget(obj1, 0, 0, 1, 1)
  layout.addWidget(obj2, 0, 1, 1, 6)
  layout.addWidget(obj3, 0, 7, 1, 6)
  </code></pre>
  
  <p><code>obj1</code> appears bigger than <code>obj2</code> and <code>obj3</code> which are still of the same size, which is the expected behavior:</p>
  
  <pre><code>---------------------------------------------------
  |          obj1           |    obj2   |    obj3   |
  ---------------------------------------------------
  </code></pre>
  
  <p>It seems totally contradictory to the doc of <a href="http://doc.qt.io/qt-4.8/qgridlayout.html#addLayout-2" rel="nofollow noreferrer">addWidget</a> as my first solution should yield the expected behavior, no?</p>
  
  <p><strong>EDIT: Piece of code</strong></p>
  
  <pre><code>import pyqtgraph as qtg
  
  obj1 = qtg.PlotWidget()
  obj2 = qtg.PlotWidget()
  obj3 = qtg.PlotWidget()
  
  layout = QGridLayout()
  
  layout.addWIdget(obj1, 0, 0, 1, 2)
  layout.addWidget(obj2, 0, 2, 1, 1)
  layout.addWidget(obj3, 0, 3, 1, 1)
  
  box = QGroupBox()
  box.setLayout(layout)
  self.setCentralWidget(box)
  </code></pre>