Problem with filedialog for opengl application.

[Q139]

Hello,
Having problem with crash while calling file opening dialog or window gui / interface from seperate class.
Also crash if window->show comand used to show seperate gui.

@ if (m->button() == Qt::MidButton){
allowmousemove = 1;
VALUElast = move_LEFT_RIGHT;
VALUElastUP_DOWN = move_UP_DOWN;
start_mouse_move = m->globalX()- VALUElast;
start_mouse_move2 = m->globalY()- VALUElastUP_DOWN;
}

}

void OpenGLWindow::mouseReleaseEvent(QMouseEvent *w)
{
if (w->button() == Qt::MidButton){
allowmousemove = 0;
}
}

void OpenGLWindow::mouseMoveEvent(QMouseEvent *q)
{
if(allowmousemove==1){

offsetMouseX = (q->globalX()-start_mouse_move);
offsetMouseY = (q->globalY()-start_mouse_move2);

}
}

void OpenGLWindow::keyPressEvent(QKeyEvent *e){

if(e->key() == Qt::Key_F1){

CRASHLINE-> // FileTOopen = QFileDialog::getOpenFileName(); // vali fail
FileTOopen = "C:/WWW/out.txt";

   readfile();         //loe sisse fail
                      }


if(e->key() == Qt::Key_F11){     zoom++;                 }
if(e->key() == Qt::Key_F12){        zoom--;               }

if(e->key() == Qt::Key_F6){                      }

}

OpenGLWindow::~OpenGLWindow()
{
delete m_device;
}
//! [2]
void OpenGLWindow::render(QPainter *painter)
@

That line // evokes crash, what to do different or proper to avoid this problem , app is rendering opengl while calling, minigw compiler.