Made use of plain text consistent.

IPython/frontend/qt/console/completion_lexer.py

@@ -31,7 +31,7 b' class CompletionLexer(object):'
                 not string.endswith('\n'):
             reversed_tokens.pop(0)
         
-        current_op = unicode()
+        current_op = ''
         for token, text in reversed_tokens:
 
             if is_token_subtype(token, Token.Name):
@@ -39,14 +39,14 b' class CompletionLexer(object):'
                 # Handle a trailing separator, e.g 'foo.bar.'
                 if current_op in self._name_separators:
                     if not context:
-                        context.insert(0, unicode())
+                        context.insert(0, '')
 
                 # Handle non-separator operators and punction.
                 elif current_op:
                     break
 
                 context.insert(0, text)
-                current_op = unicode()
+                current_op = ''
 
             # Pygments doesn't understand that, e.g., '->' is a single operator
             # in C++. This is why we have to build up an operator from

IPython/frontend/qt/console/completion_widget.py

@@ -112,7 +112,7 b' class CompletionWidget(QtGui.QListWidget):'
     def _update_current(self):
         """ Updates the current item based on the current text.
         """
-        prefix = self._current_text_cursor().selectedText()
+        prefix = self._current_text_cursor().selection().toPlainText()
         if prefix:
             items = self.findItems(prefix, (QtCore.Qt.MatchStartsWith | 
                                             QtCore.Qt.MatchCaseSensitive))

IPython/frontend/qt/console/frontend_widget.py

@@ -274,7 +274,7 b' class FrontendWidget(HistoryConsoleWidget):'
             cursor = self.textCursor()
         cursor.movePosition(QtGui.QTextCursor.StartOfLine, 
                             QtGui.QTextCursor.KeepAnchor)
-        text = unicode(cursor.selectedText())
+        text = str(cursor.selection().toPlainText())
         return self._completion_lexer.get_context(text)
 
     def _interrupt_kernel(self):