Traceback (most recent call last):
  File "mysoft.py", line 32, in bookLoad
    book.setUrl(QtCore.QUrl(y))
TypeError: arguments did not match any overloaded call:
  QUrl(): too many arguments
  QUrl(QString): argument 1 has unexpected type 'QTreeWidgetItem'
  QUrl(QUrl): argument 1 has unexpected type 'QTreeWidgetItem'
  QUrl(QString, QUrl.ParsingMode): argument 1 has unexpected type 'QTreeWidgetItem'

def bookLoad(y):
    book.setUrl(QtCore.QUrl(y)) 


book = QWebView()
book.load(QtCore.QUrl(f)) # Дефолтная страница.


QtCore.QObject.connect(tree, QtCore.SIGNAL('itemClicked(QTreeWidgetItem *, int)'), bookLoad)