My first qt question: how can I convert a MDIsubwindow to popup windows back and forc

[alxwang]

Sure.
When I need to move the MDIsubWindow to desktop:

QMdiArea *area = new QMdiArea();
	QMdiSubWindow *subWin = this->mdiArea->activeSubWindow();
// I did try to remove this subwin from mdiArea first but not difference
	area->addSubWindow(subWin);
	XSubWindow *win = new XSubWindow();
	win->setMdiArea(area);
	win->show();
	connect(win, SIGNAL(returnSubWindow(QMdiSubWindow*)), this, SLOT(getReturnedSubWindow(QMdiSubWindow*)));

QMdiArea *area = new QMdiArea();
	QMdiSubWindow *subWin = this->mdiArea->activeSubWindow();
// I did try to remove this subwin from mdiArea first but not difference
	area->addSubWindow(subWin);
	XSubWindow *win = new XSubWindow();
	win->setMdiArea(area);
	win->show();
	connect(win, SIGNAL(returnSubWindow(QMdiSubWindow*)), this, SLOT(getReturnedSubWindow(QMdiSubWindow*)));

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XSubWindow is just a QMainWindow with
closeEvent like

void XSubWindow::closeEvent(QCloseEvent *event)
{
	emit returnSubWindow(this->mdiArea->activeSubWindow());
	event->accept();
 
}

void XSubWindow::closeEvent(QCloseEvent *event)
{
	emit returnSubWindow(this->mdiArea->activeSubWindow());
	event->accept();

}

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to handle the returnSubWindow in main MDI window:

void MainWindow::getReturnedSubWindow(QMdiSubWindow *rwin)
{
	this->mdiArea->addSubWindow(rwin);
 
}

void MainWindow::getReturnedSubWindow(QMdiSubWindow *rwin)
{
	this->mdiArea->addSubWindow(rwin);

}

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The content of MDIsubWindow is ether a WEBkit window:

XWebWidget *child = new XWebWidget;
	child->setWindowTitle("Demo");
    mdiArea->addSubWindow(child);

XWebWidget *child = new XWebWidget;
	child->setWindowTitle("Demo");
    mdiArea->addSubWindow(child);

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or
QGraphicsScene only contains a picture.

QGraphicsScene scene;
    scene.setSceneRect(-300, -300, 600, 600);
    scene.setItemIndexMethod(QGraphicsScene::NoIndex);
 
	QGraphicsView *view = new QGraphicsView;
	view->setWindowTitle("Demo Bid Page");
	view->setRenderHint(QPainter::Antialiasing);
    view->setBackgroundBrush(QPixmap(":/images/demo.jpg"));
 
    mdiArea->addSubWindow(view);

QGraphicsScene scene;
    scene.setSceneRect(-300, -300, 600, 600);
    scene.setItemIndexMethod(QGraphicsScene::NoIndex);
	
	QGraphicsView *view = new QGraphicsView;
	view->setWindowTitle("Demo Bid Page");
	view->setRenderHint(QPainter::Antialiasing);
    view->setBackgroundBrush(QPixmap(":/images/demo.jpg"));

    mdiArea->addSubWindow(view);

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