[PyQt] Best way to display additional window

[Filip Gruszczyński]

I would like to be able to display a very simple widget: widget with
an image drawn inside (it is supposed to display an image, that was
previously visible only on a thumbnail). This should be opened in a
new window.

First thing I tried was QDialog. But it seems, that just painting on
it using paintEvent is not enough and it disappears (though I used
exec_ on it). So I went back to a widget, checked the docs for making
it a standalone window and tried something like this:

class ImageViewer(QWidget):

	def __init__(self, resource, parent):
		QWidget.__init__(self, parent, Qt.Popup)
		self.__resource = resource
		self.repaint()
		
	def paintEvent(self, event):
		painter = QPainter(self)
		image = QImage(self.__resource.file())
		self.resize(image.size())
		painter.drawImage(QRect(QPoint(0, 0), image.size()), image)

This should be modal, top-level window. I call show on it, but it
appears only for a moment to disappear after that. I do:

			column = event.pos().x() /  self.RectangleFullWidth
			row = event.pos().y() /  self.RectangleFullHeight
			image = ImageViewer(self.__drawn[(column, row)], self)
			image.show()

(I am picking thumbnail from the displayed and trying to display it in full).

I'd really appreciate some advice on how can I achieve a stand alone
window for displaying some stuff, e.g. an Image. As long as there are
some widgets inside it's easy, because dialog is enough. But this
doesn't.

-- 
Filip Gruszczyński