title: Qt Creator: Design changes not showing when run
body: <p>I had made some changes on the '<strong>mainwindow.ui</strong>' file from the folder: 'Forms'. 
  I've added a new title entitled 'File' and there only two simple options, 'Add Fractal' and 'Exit'</p>
  
  <p><img src="https://i.stack.imgur.com/43NyK.png" alt="enter image description here"></p>
  
  <p>You can also see that both are on the mainwindow.ui file:<img src="https://i.stack.imgur.com/6TujE.png" alt="enter image description here"></p>
  
  <p>But when I run the project, the window is not showing as I wish. Tabs are not showing.</p>
  
  <p><img src="https://i.stack.imgur.com/M34XD.png" alt="enter image description here"></p>
  
  <p>I had build, rebuild and make, and still have this strange thing.
  Can anyone give me a hand?</p>
  
  <p><strong>mainwindow.h</strong></p>
  
  <pre><code>#ifndef MAINWINDOW_H
  #define MAINWINDOW_H
  
  #include &lt;QMainWindow&gt;
  
  namespace Ui {
      class MainWindow;
  }
  
  class MainWindow : public QMainWindow
  {
      Q_OBJECT
  
  public:
      explicit MainWindow(QWidget *parent = 0);
      ~MainWindow();
  
  private:
      Ui::MainWindow *ui;
      void createActions();
      void createMenus();
      // Widgets i layouts
      QWidget *centralWidget;
      // Accions associades als menus
      QAction *exitAct;
      // Menus principals
      QMenu *fileMenu;
  };
  
  #endif // MAINWINDOW_H
  </code></pre>
  
  <p><strong>mainwindow.cpp</strong></p>
  
  <pre><code>#include "mainwindow.h"
  #include "ui_mainwindow.h"
  
  MainWindow::MainWindow(QWidget *parent) :
      QMainWindow(parent),
      ui(new Ui::MainWindow)
  {
      ui-&gt;setupUi(this);
      centralWidget = new QWidget;
      setCentralWidget(centralWidget); createActions();
      createMenus();
      setWindowTitle(tr("Practica 1: GiVD 2011-2012"));
      resize(640, 480);
  }
  
  void MainWindow::createActions() {
      exitAct = new QAction(tr("&amp;Exit"), this);
      exitAct-&gt;setShortcut(tr("Ctrl+Q"));
      exitAct-&gt;setStatusTip(tr("Sortir del programa"));
      connect(exitAct, SIGNAL(triggered()), qApp, SLOT(closeAllWindows()));
  }
  
  void MainWindow::createMenus()
  {
      fileMenu = menuBar()-&gt;addMenu(tr("&amp;File"));
      fileMenu-&gt;addSeparator();
      // Per a cada nou submenú has de fer un addAction
      fileMenu-&gt;addAction(exitAct);
  }
  
  MainWindow::~MainWindow()
  {
      delete ui;
  }
  </code></pre>
  
  <p><strong>main.cpp</strong></p>
  
  <pre><code>#include &lt;QtGui/QApplication&gt;
  #include "mainwindow.h"
  
  int main(int argc, char *argv[])
  {
      QApplication a(argc, argv);
      MainWindow w;
      w.show();
  
      return a.exec();
  }
  </code></pre>
  
  <p><strong>mainwindow.ui</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;ui version="4.0"&gt;
   &lt;class&gt;MainWindow&lt;/class&gt;
   &lt;widget class="QMainWindow" name="MainWindow"&gt;
    &lt;property name="geometry"&gt;
     &lt;rect&gt;
      &lt;x&gt;0&lt;/x&gt;
      &lt;y&gt;0&lt;/y&gt;
      &lt;width&gt;400&lt;/width&gt;
      &lt;height&gt;300&lt;/height&gt;
     &lt;/rect&gt;
    &lt;/property&gt;
    &lt;property name="windowTitle"&gt;
     &lt;string&gt;MainWindow&lt;/string&gt;
    &lt;/property&gt;
    &lt;widget class="QWidget" name="centralWidget"/&gt;
    &lt;widget class="QMenuBar" name="menuBar"&gt;
     &lt;property name="geometry"&gt;
      &lt;rect&gt;
       &lt;x&gt;0&lt;/x&gt;
       &lt;y&gt;0&lt;/y&gt;
       &lt;width&gt;400&lt;/width&gt;
       &lt;height&gt;22&lt;/height&gt;
      &lt;/rect&gt;
     &lt;/property&gt;
     &lt;widget class="QMenu" name="menuFile"&gt;
      &lt;property name="title"&gt;
       &lt;string&gt;File&lt;/string&gt;
      &lt;/property&gt;
      &lt;addaction name="actionAdd_Fractal"/&gt;
      &lt;addaction name="actionExit"/&gt;
     &lt;/widget&gt;
     &lt;addaction name="menuFile"/&gt;
    &lt;/widget&gt;
    &lt;widget class="QToolBar" name="mainToolBar"&gt;
     &lt;attribute name="toolBarArea"&gt;
      &lt;enum&gt;TopToolBarArea&lt;/enum&gt;
     &lt;/attribute&gt;
     &lt;attribute name="toolBarBreak"&gt;
      &lt;bool&gt;false&lt;/bool&gt;
     &lt;/attribute&gt;
    &lt;/widget&gt;
    &lt;widget class="QStatusBar" name="statusBar"/&gt;
    &lt;action name="actionAdd_Fractal"&gt;
     &lt;property name="text"&gt;
      &lt;string&gt;Add Fractal&lt;/string&gt;
     &lt;/property&gt;
    &lt;/action&gt;
    &lt;action name="actionExit"&gt;
     &lt;property name="text"&gt;
      &lt;string&gt;Exit&lt;/string&gt;
     &lt;/property&gt;
    &lt;/action&gt;
   &lt;/widget&gt;
   &lt;layoutdefault spacing="6" margin="11"/&gt;
   &lt;resources/&gt;
   &lt;connections/&gt;
  &lt;/ui&gt;
  </code></pre>