Mdichild related problem

DomDom

Hi,

I got a mdichild class (derived from QPlainTextEdit).
When I try to "play" with it (using setTabStopWidth ortrying to move its cursor for example).
It crashed in QScopedPointer.h in the function

@ inline T *data() const
{
return d; <============ crash here with an invalid "this" value .
}@
the crash only appends if my mdichild already exists (i.e. if found in mdiArea->subWindowList() );
When the mdichild does not exist yet and just created and add with mdiArea->addSubWindow(child); evrything is

Is it a thread related problem ?
Do i need to do something special (like waiting for the mdichild to show up) before trying to work with it ?

Any help will be appreciated.
Thanks in advance

giesbert

Please give us a bit more information.

Are you working with worker threads?
What do they do?

DomDom

No, I don't use worker threads at all.
I started with this sample :
"http://qt-project.org/doc/qt-4.8/mainwindows-mdi.html":http://qt-project.org/doc/qt-4.8/mainwindows-mdi.html

And I'm trying to set the tab width here :

@ void MainWindow::open()
{
QString fileName = QFileDialog::getOpenFileName(this);
if (!fileName.isEmpty()) {
QMdiSubWindow *existing = findMdiChild(fileName);
if (existing) {
mdiArea->setActiveSubWindow(existing);
existing->MyFunctionToSetTabWidth(); <---Here
return;
}

     MdiChild *child = createMdiChild();
     if (child->loadFile&#40;fileName&#41;) {
         statusBar()->showMessage(tr("File loaded"), 2000);
         child->show();
     } else {
         child->close();
     }
 }

}
@

giesbert

Hm,
in general, this function looks good. Maybe it's in the sourroundings somewhere. Did you debug the whole thing and check, whether existing points to a valid object?

DomDom

Thanks a lot, you were right, it was in the surroundings.
It was a bad cast. findMdiChild returns a QMdiSubWindow and not directly a widget. The solution was to cast the widget and not directly the subwindow like this :

@ QMdiSubWindow *subw = findMdiChild(fileName);
if (subw != NULL)
{
existing = qobject_cast<MdiChild *> (subw->widget());
}@