issue focusing QLineEdit rendered to QGraphicsScene

I render Qt gui elements on my own 3d application screen by rendering Qt stuff to QImage and then drawing that on the screen. I redirect input to QGraphicsScene, but not everything works. Clicking buttons works fine while clicking QLineEdit or web page elements in QWebView doesnt. However doubleclick seems to work - doubleclicked QLineEdit would select some text, but still would not gain focus. Also even if key events are sent - no text is entered, probably due to lack of focus. What could be causing this?