View Full Version : Firefox crush when try to show dialog from Qt GUI library (Linux ubuntu)

25th July 2010, 06:42

I have Qt GUI library which shows dialogs such as login. We use it with Firefox which calls the Qt library that should show a dialog. But at this point Firefox is closed with segmantation error.

I can use my Qt GUI library from non-Qt application by providing the QApplication inside the library and it works. I have the GTK 2.0 installed.

Thanks for any help you provide.


25th July 2010, 08:28
That's way too few information to give a good answer.

So, install and/or rebuild the respective packages (firefox, qt, etc...) with debug information.
Then run it all through gdb and get a backtrace. Using the backtrace you can already see where the problem might be. If not, use the information to step through the program and look at the registers and variables.

A segmentation fault happens when you try to access memory you're not supposed to access (like in an uninitialized pointer)

25th July 2010, 08:34
Thanks. How do I add debug information to my Qt library? Could it be related to the gtk-qt?

25th July 2010, 09:22
OK it is crashing when I create the QApplication object:

QApplication * a = new QApplication(NULL,NULL);

25th July 2010, 09:58
Passing it two nulls is probably what's causing the crash. You can't pass arbitrary values to objects and expect them to work.

25th July 2010, 10:58
The full code is:

QApplication * a = 0;
if (!qApp){

int argc = 1;

char *argv[] = { "asePinDialog", NULL };

a = new QApplication(argc,argv);

//QApplication b(argc,argv);


m_iLastSlotId = aseData.slotID;

ChangePin *pinDlg = new ChangePin(aseData);

m_pOpenDialog = pinDlg;


bool bRet = (pinDlg->result() == QDialog::Accepted);

delete pinDlg;

m_pOpenDialog = NULL;

m_iLastSlotId = 0;



delete a;

a = 0;


return bRet;