title: adding widget dynamically in qt
body: <p>I have a small problem with adding widget to QMainWindow. 
  When i do it like that:</p>
  
  <pre><code>wsk_mainStatki = new mainStatki(this);
  wsk_mainStatki -&gt;setGeometry(0,0,400,300);
  this-&gt;layout()-&gt;addWidget(wsk_mainStatki);
  </code></pre>
  
  <p>it's ok but i get warning:</p>
  
  <blockquote>
    <p>QMainWindowLayout::addItem: Please use the public QMainWindow API instead</p>
  </blockquote>
  
  <p>this is my game class</p>
  
  <pre><code>    #include "game.h"
  
      game::game()
      {
          setGeometry(200, 200, 400, 300);
          setWindowTitle("Statki");
          wsk_mainStatki = new mainStatki(this);
          wsk_mainStatki -&gt;setGeometry(0,0,400,300);
          this-&gt;layout()-&gt;addWidget(wsk_mainStatki);
      }
  </code></pre>
  
  <p>game header</p>
  
  <pre><code>#ifndef WIDGET1_H
  #define WIDGET1_H
  #include "k_plansza.h"
  #include "mainStatki.h"
  #include "settings.h"
  #include &lt;QApplication&gt;
  #include &lt;QMainWindow&gt;
  
  class game : public QMainWindow
  {
      public:
          game();
          ~game() {};
      private:
          mainStatki *wsk_mainStatki;
          settings *wsk_settings;
  };
  
  #endif // WIDGET1_H
  </code></pre>
  
  <p>mainstatki class</p>
  
  <pre><code>#include "mainstatki.h"
  
  mainStatki::mainStatki(QWidget *parent){
      setupUi(this);
      connect(closeButton, SIGNAL(clicked()), parent, SLOT(close()));
  }
  </code></pre>
  
  <p>mainstatki header</p>
  
  <pre><code>#ifndef MAINSTATKI_H
  #define MAINSTATKI_H
  
  #include &lt;QWidget&gt;
  #include "ui_mainStatki.h"
  
  class mainStatki : public QWidget, public Ui::mainStatki
  {
      Q_OBJECT
  public:
      mainStatki(QWidget *parent);
  
  };
  
  #endif // MAINSTATKI_H
  </code></pre>
  
  <p>How it should look? </p>