WebKit displays Quicktime plugin in correctly when WebView is placed in a layout.

When using an object of the "QWebView" class and displaying a page which makes use of the Quicktime Plugin, the content displayed by the plugin (H264 video coming from an IP Camera) appears on a wrong fixed position instead of the correct position given by the QWebView instance. However, this happens only when QWebView is placed inside a layout. If the QWebView object is shown without being placed into a layout, everything works perfect.
I tried this with my own code and with the QtWebkit browser example and the behaviour is the same.
I don't know if this could be a bug of QtWebkit or a bug of Quicktime plugin.