I want to make child widgets re-sizable along with the parent. Could you help me ?

This is my widget constructor:

Qt Code: 
  1. CustomWidget::CustomWidget(QWidget *parent) :
  2.     QWidget(parent)
  3. {
  4.  
  5.     m_button_edit.setText(tr("Edit"));
  6.     m_button_all.setText(tr("All"));
  7.     m_button_cancel.setText(tr("Cancel"));
  8.  
  9.  
  10.     InitializeModels();
  11.  
  12.     m_table1 = new QTableView(this);
  13.     m_table2 = new QTableView(this);
  14.  
  15.     SetTables();
  16.  
  17.     QSplitter *splitter = new QSplitter(Qt::Vertical, this);
  18.     splitter->addWidget(m_table1);
  19.     QWidget *temp = new QWidget(this);
  20.     QGridLayout *layout_table2 = new QGridLayout(this);
  21.     layout_table2->addWidget(m_table2, 0, 0, 1, 3);
  22.     layout_table2->addWidget(&m_button_edit,   1, 0, 1, 1);
  23.     layout_table2->addWidget(&m_button_all,    1, 1, 1, 1);
  24.     layout_table2->addWidget(&m_button_cancel, 1, 2, 1, 1);
  25.     temp->setLayout(layout_table2);
  26.     splitter->addWidget(temp);
  27.  
  28. }
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I got some small window which I should stretch to see the items inside and they have a fixed size.
If you have any other suggestion about better approach in setting widget positions than in my case I would be glad if you share.