Hi,

So to avoid confusion and to make it simple I created a simple example with 2 buttons and that's all. The code was first created by QT creator (QT4 gui application) all default settings. Then 2 buttons were added to the gui with qt designer. Finally one slot created in creator using the option "go to slot".

here is main.cpp
Qt Code: 
  1. #include <QtGui/QApplication>
  2. #include "mainwindow.h"
  3.  
  4. int main(int argc, char *argv[])
  5. {
  6.     QApplication a(argc, argv);
  7.     MainWindow w;
  8.     w.show();
  9.     return a.exec();
  10. }
To copy to clipboard, switch view to plain text mode 
mainwindow.cpp
Qt Code: 
  1. #include "mainwindow.h"
  2. #include "ui_mainwindow.h"
  3. #include <QtGui>
  4.  
  5. MainWindow::MainWindow(QWidget *parent) :
  6.     QMainWindow(parent),
  7.     ui(new Ui::MainWindow)
  8. {
  9.     ui->setupUi(this);
  10.     ui->pushButton->setText("I changed the text");
  11.     setWindowTitle("This is the title I would like to be");
  12. }
  13.  
  14. MainWindow::~MainWindow()
  15. {
  16.     delete ui;
  17. }
  18.  
  19. void MainWindow::changeEvent(QEvent *e)
  20. {
  21.     QMainWindow::changeEvent(e);
  22.     switch (e->type()) {
  23.     case QEvent::LanguageChange:
  24.         ui->retranslateUi(this);
  25.         break;
  26.     default:
  27.         break;
  28.     }
  29. }
  30.  
  31. void MainWindow::on_pushButton_2_clicked()
  32. {
  33.     QFileDialog mydialog;
  34.     QString fn = mydialog.getOpenFileName(this, tr("Open File"),"/home",tr("Images (*.png *.xpm *.jpg)"));
  35. }
To copy to clipboard, switch view to plain text mode 
mainwindow.h
Qt Code: 
  1. #ifndef MAINWINDOW_H
  2. #define MAINWINDOW_H
  3.  
  4. #include <QMainWindow>
  5.  
  6. namespace Ui {
  7.     class MainWindow;
  8. }
  9.  
  10. class MainWindow : public QMainWindow {
  11.     Q_OBJECT
  12. public:
  13.     MainWindow(QWidget *parent = 0);
  14.     ~MainWindow();
  15.  
  16. protected:
  17.     void changeEvent(QEvent *e);
  18.  
  19. private:
  20.     Ui::MainWindow *ui;
  21.  
  22. private slots:
  23.     void on_pushButton_2_clicked();
  24. };
  25.  
  26. #endif // MAINWINDOW_H
To copy to clipboard, switch view to plain text mode 

And here is what's happening: when selecting the second button opening a qfiledialogue using static function getopenfilename the label of the first button and the window title are reset (using dynamic qfiledialog does the same as far as I can tell).

Either there is something I am missing due to my lack of knowledge or this is a bug.