Hi to all, I've centos 6.4 in VM and Qt 5.3.2. I am trying to build SDI app. fallowing is the code:-
sdiapMainwindow.pro:-

Qt Code: 
  1. QT       += core gui
  2.  
  3. greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
  4.  
  5. TARGET = sdiapp
  6. TEMPLATE = app
  7.  
  8.  
  9. SOURCES += main.cpp\
  10.         sdiappmainwindow.cpp
  11.  
  12. HEADERS  += sdiappmainwindow.h
  13.  
  14. FORMS    += sdiappmainwindow.ui
  15.  
  16. RESOURCES += \
  17.     sdimainiwndow_rsc.qrc
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sdiappMainwindow.h:-

Qt Code: 
  1. #ifndef SDIAPPMAINWINDOW_H
  2. #define SDIAPPMAINWINDOW_H
  3.  
  4. #include <QMainWindow>
  5.  
  6. namespace Ui {
  7. class sdiappMainWindow;
  8. }
  9.  
  10. class sdiappMainWindow : public QMainWindow
  11. {
  12.     Q_OBJECT
  13.  
  14. private slots:
  15.     void newfile();
  16.     void helpAbout();
  17.  
  18. protected:
  19.  
  20.     void closeEvent(QCloseEvent *event);
  21.     bool isSafeToClose();
  22. public:
  23.     explicit sdiappMainWindow(QWidget *parent = 0);
  24.     ~sdiappMainWindow();
  25.  
  26.     void connectActions();
  27. private:
  28.     Ui::sdiappMainWindow *ui;
  29. };
  30.  
  31. #endif // SDIAPPMAINWINDOW_H
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sdiappMainwindow.cpp :-
----------------------------

Qt Code: 
  1. #include "sdiappmainwindow.h"
  2. #include "ui_sdiappmainwindow.h"
  3. #include <QMessageBox>
  4. #include <QApplication>
  5.  
  6. #include <QCloseEvent>
  7.  
  8. sdiappMainWindow::sdiappMainWindow(QWidget *parent) :
  9.     QMainWindow(parent),
  10.     ui(new Ui::sdiappMainWindow)
  11. {
  12.     ui->setupUi(this);
  13.  
  14.     setAttribute(Qt::WA_DeleteOnClose);
  15.     setWindowTitle(QString("%1[*] %2").arg("unamed - ").arg("SDI"));
  16.     connect(ui->textEditSDIMainWindow->document(), SIGNAL(modificationChanged(bool)), this,  SLOT(setWindowModified(bool)) );
  17.  
  18.     connectActions();
  19. }
  20. void sdiappMainWindow::closeEvent(QCloseEvent *event)
  21. {
  22.     if( isSafeToClose())
  23.         event->accept();
  24.     else
  25.         event->ignore();
  26. }
  27.  
  28. bool sdiappMainWindow::isSafeToClose()
  29. {
  30.     if(isWindowModified())
  31.     {
  32.         switch(QMessageBox::warning(this, "SDI", "the window has unsaved changes\n"
  33.                                     " do you want to save changes before it is closed", QMessageBox::Discard | QMessageBox::Cancel))
  34.         {
  35.         case QMessageBox::Cancel : return false; break;
  36.         default : return true;
  37.         }
  38.     }
  39.     return true;
  40. }
  41.  
  42. void sdiappMainWindow::connectActions()
  43. {
  44.       connect( ui->actionE_xtit, SIGNAL(triggered()), qApp, SLOT(closeAllWindows()) );
  45.       connect( ui->action_Close, SIGNAL(triggered()), this, SLOT(close()) );
  46. }
  47.  
  48.  
  49.  
  50. sdiappMainWindow::~sdiappMainWindow()
  51. {
  52.     delete ui;
  53. }
  54.  
  55. void sdiappMainWindow::newfile()
  56. {
  57.   (new sdiappMainWindow())->show();
  58. }
  59.  
  60. void  sdiappMainWindow::helpAbout()
  61. {
  62.  
  63. }
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inteface is :
sdimainwnd.png
this code runs successfully bit when closing it show following error :-
-----------------------------------------------------------------------------
ouotput is:-
Qt Code: 
  1. Starting /opt/project/qt/build-sdiapp-Desktop_Qt_5_3_GCC_64bit-Debug/sdiapp...
  2.  
  3. (<unknown>:125658): Gtk-WARNING **: Attempt to load unknown IM context type 'gtk-im-context-none'
  4. *** glibc detected *** /opt/project/qt/build-sdiapp-Desktop_Qt_5_3_GCC_64bit-Debug/sdiapp: munmap_chunk(): invalid pointer: 0x00007fffeb1757e0 ***
  5. ======= Backtrace: =========
  6. /lib64/libc.so.6[0x36694760e6]
  7. /opt/project/qt/build-sdiapp-Desktop_Qt_5_3_GCC_64bit-Debug/sdiapp[0x405f46]
  8. /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5(_ZN7QObject5eventEP6QEvent+0x438)[0x7f4f908dca08]
  9. /opt/Qt/5.3/gcc_64/lib/libQt5Widgets.so.5(_ZN7QWidget5eventEP6QEvent+0xc2)[0x7f4f915b24d2]
  10. /opt/Qt/5.3/gcc_64/lib/libQt5Widgets.so.5(_ZN11QMainWindow5eventEP6QEvent+0x7b)[0x7f4f916d42cb]
  11. /opt/Qt/5.3/gcc_0x616)[0x7f4f9157dd46]
  12. ............
  13. /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5(_ZN16QCoreApplication14notifyInternalEP7QObjectP6QEvent+0x84)[0x7f4f908a8fc4]
  14. /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5(_ZN23QCoreApplicationPrivate16sendPostedEventsEP7QObjectiP11QThreadData+0x258)[0x7f4f908abb48]
  15. /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5(+0x329253)[0x7f4f90903253]
  16. /lib64/libglib-2.0.so.0(g_main_context_dispatch+0x22e)[0x366a838f0e]
  17. /lib64/libglib-2.0.so.0[0x366a83c938]
  18. /lib64/libglib-2.0.so.0(g_main_context_iteration+0x7a)[0x366a83ca3a]
  19. /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5(_ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE+0x64)[0x7f4f90903684]
  20. /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5(_ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE+0xcb)[0x7f4f908a71db]
  21. /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5(_ZN16QCoreApplication4execEv+0x85)[0x7f4f908ac0a5]
  22. /opt/project/qt/build-sdiapp-Desktop_Qt_5_3_GCC_64bit-Debug/sdiapp[0x405994]
  23. /lib64/libc.so.6(__libc_start_main+0xfd)[0x366941ecdd]
  24. /opt/project/qt/build-sdiapp-Desktop_Qt_5_3_GCC_64bit-Debug/sdiapp[0x405889]
  25. ======= Memory map: ========
  26.  
  27. .....
  28. 7f4f863cd000-7f4f8640e000 rw-p 00000000 00:00 0 
  29. 7f4f8640e000-7f4f86450000 r-xp 00000000 08:03 1593842                    /opt/Qt/5.3/gcc_64/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so
  30. 7f4f86450000-7f4f8664f000 ---p 00042000 08:03 1593842                    /opt/Qt/5.3/gcc_64/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so
  31. 7f4f8664f000-7f4f86651000 r--p 00041000 08:03 1593842                    /opt/Qt/5.3/gcc_64/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so
  32. 7f4f86651000-7f4f86652000 rw-p 00043000 08:03 1593842                    /opt/Qt/5.3/gcc_64/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so
  33. 7f4f86652000-7f4f866af000 r-xp 00000000 08:03 140781                     /lib64/libfreebl3.so
  34. 7f4f866af000-7f4f868ae000 ---p 0005d000 08:03 140781                     /lib64/libfreebl3.so
  35. 7f4f868ae000-7f4f868af000 r--p 0005c000 08:03 140781                     /lib64/libfreebl3.so
  36. 7f4f868af000-7f4f868b0000 rw-p 0005d000 08:03 140781                     /lib64/libfreebl3.so
  37. 7f4f868b0000-7f4f868b4000 rw-p 00000000 00:00 0 
  38. 7f4f868b4000-7f4f868bb000 r-xp 00000000 08:03 140782                     /lib64/libcrypt-2.12.so
  39. 7f4f868bb000-7f4f86abb000 ---p 00007000 08:03 140782                     /lib64/libcrypt-2.12.so
  40. 7f4f86abb000-7f4f86abc000 r--p 00007000 08:03 140782                     /lib64/libcrypt-2.12.so
  41. 7f4f86abc000-7f4f86abd000 rw-p 00008000 08:03 140782                     /lib64/libcrypt-2.12.so
  42. 7f4f86abd000-7f4f86aeb000 rw-p 00000000 00:00 0 
  43. 7f4f86aeb000-7f4f86af0000 r-xp 00000000 08:03 4065985                    /usr/lib64/gtk-2.0/modules/libcanberra-gtk-module.so
  44. 7f4f86af0000-7f4f86cf0000 ---p 00005000 08:03 4065985                    /usr/lib64/gtk-2.0/modules/libcanberra-gtk-module.so
  45. 7f4f86cf0000-7f4f86cf1000 rw-p 00005000 08:03 4065985                    /usr/lib64/gtk-2.0/modules/libcanberra-gtk-module.so
  46. 7f4f86cf1000-7f4f86d13000 r-xp 00000000 08:03 3952264                    /usr/lib64/libdbus-glib-1.so.2.1.0
  47. 7f4f86d13000-7f4f86f12000 ---p 00022000 08:03 3952264                    /usr/lib64/libdbus-glib-1.so.2.1.0
  48. 7f4f86f12000-7f4f86f14000 rw-p 00021000 08:03 3952264                    /usr/lib64/libdbus-glib-1.so.2.1.0
  49. 7f4f905b6000-7f4f905b8000 rw-p 0021d000 08:03 1457483                    /opt/Qt/5.3/gcc_64/lib/libicui18n.so.52.1
  50. 7f4f905b8000-7f4f905bc000 rw-p 00000000 00:00 0 
  51. 7f4f905bc000-7f4f905bd000 r--s 00000000 08:03 2363930                    /var/cache/fontconfig/ac68f755438cc3dc5a526084839fc7ca-le64.cache-3
  52. 7f4f905bd000-7f4f905cf000 r--s 00000000 08:03 2361223                    /var/cache/fontconfig/74717c444f6fd72454fa9c9c0ee01ca7-le64.cache-3
  53. 7f4f905cf000-7f4f905d6000 r--s 00000000 08:03 2360868                    /var/cache/fontconfig/928306c3ad40271d946e41014a49fc28-le64.cache-3
  54. 7f4f905d6000-7f4f905d7000 r--s 00000000 08:03 2363928                    /var/cache/fontconfig/1248881498ac025e45c3042f6afe9284-le64.cache-3
  55. 7f4f905d7000-7f4f905da000 r--s 00000000 08:03 2363905                    /var/cache/fontconfig/beeeeb3dfe132a8a0633a017c99ce0c0-le64.cache-3
  56. 7f4f905da000-7f4f90aea000 r-xp 00000000 08:03 1458026                    /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5.3.2
  57. 7f4f90aea000-7f4f90ce9000 ---p 00510000 08:03 1458026                    /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5.3.2
  58. 	.....................
  59. 7f4f90ce9000-7f4f90cf3000 r--p 0050f000 08:03 1458026                    /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5.3.2
  60. 7f4f90cf3000-7f4f90d0c000 rw-p 00519000 08:03 1458026                    /opt/Qt/5.3/gcc_64/lib/libQt5Core.so.5.3.2
  61. 7f4f90d0c000-7f4f90d0e000 rw-p 00000000 00:00 0 
  62. 7f4f90d0e000-7f4f91209000 r-xp 00000000 08:03 1458031                    /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5.3.2
  63. 7f4f91209000-7f4f91409000 ---p 004fb000 08:03 1458031                    /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5.3.2
  64. 7f4f91409000-7f4f9141f000 r--p 004fb000 08:03 1458031                    /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5.3.2
  65. 7f4f9141f000-7f4f91431000 rw-p 00511000 08:03 1458031                    /opt/Qt/5.3/gcc_64/lib/libQt5Gui.so.5.3.2
  66. 7f4f91431000-7f4f91434000 rw-p 00000000 00:00 0 
  67. 7f4f91434000-7f4f91a2b000 r-xp 00000000 08:03 1458050                    /opt/Qt/5.3/gcc_64/lib/libQt5Widgets.so.5.3.2
  68. 7f4f91a2b000-7f4f91c2b000 ---p 005f7000 08:03 1458050                    /opt/Qt/5.3/gcc_64/lib/libQt5Widgets.so.5.3.2
  69. 7f4f91c2b000-7f4f91c55000 r--p 005f7000 08:03 1458050                    /opt/Qt/5.3/gcc_64/lib/libQt5Widgets.so.5.3.2
  70. 7f4f91c55000-7f4f91c76000 rw-p 00621000 08:03 1458050                    /opt/Qt/5.3/gcc_64/lib/libQt5Widgets.so.5.3.2
  71. 7f4f91c76000-7f4f91c78000 rw-p 00000000 00:00 0 
  72. 7fffeb163000-7fffeb178000 rw-p 00000000 00:00 0                          [stack]
  73. 7fffeb1ff000-7fffeb200000 r-xp 00000000 00:00 0                          [vdso]
  74. ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]
  75. The program has unexpectedly finished.
  76. /opt/project/qt/build-sdiapp-Desktop_Qt_5_3_GCC_64bit-Debug/sdiapp crashed
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