title: Multiple Widgets in QGridLayout limitation
body: <p>I try to make a own widget for block scanning like a defrag software. 
  I have now a problem with limitation of widgets in QT.</p>
  
  <p>My current approach is:</p>
  
  <p>r = 200 / c = 83</p>
  
  <pre><code>void QScanBoard::setupLayout()
  {
  
      this-&gt;setAttribute(Qt::WA_LayoutUsesWidgetRect);
      this-&gt;setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Minimum);
  
      gridTable = new QGridLayout;
  
      gridTable-&gt;setSpacing(0);
      gridTable-&gt;setMargin(0);
      gridTable-&gt;setContentsMargins(0, 0, 0, 0);
      gridTable-&gt;setSizeConstraint(QLayout::SetFixedSize);
  
      this-&gt;setLayout(gridTable);
  }
  
  void QScanBoard::createTiles()
  {
      for (unsigned int r = 0; r &lt; m_numRows; ++r)
      {
          m_tiles += QList&lt;QScanTile*&gt;{};
          for (unsigned int c = 0; c &lt; m_numCols; ++c)
          {
              // add a new tile to the row
              m_tiles[r] += new QScanTile({ r, c }, this);
              gridTable-&gt;addWidget(m_tiles[r][c], r, c);
  
          }
      }
      m_tiles[0][0]-&gt;setDown(true);
  
  }
  </code></pre>
  
  <p>QScanTitle is a QPushButton or also a QLabel as sample. I use a QGridLayout to place this widgets on the dialog (widget).</p>
  
  <p>If I use now 200/83 it is fast enough. If I try to set 2000/83 the software will hang. This means with 166000 widgets are too much. But sometimes I need much more. </p>
  
  <p>Any idea how to manage this? Because a widget can only have one parent I cannot add one QPushButton multiple times, I need to create it for each QGridLayout cell a new one.</p>
  
  <p>Can I set a QGridLayout without any widget inside the cells? Just a Background color?</p>