Fixed the segfaults on application exit. The BracketMatcher, CallTipWidget, and CompletionWidget were using the text control as their parents. This should not be a problem, but for some reason it resulted in problems during shutdown. I suspect that PyQt is bugged and was deleting the C++ objects a second time in the garbage collection phase after they had already been deleted automatically by the C++ layer of Qt.

IPython/frontend/qt/console/bracket_matcher.py

@@ -18,18 +18,19 b' class BracketMatcher(QtCore.QObject):'
     # 'QObject' interface
     #--------------------------------------------------------------------------
 
-    def __init__(self, parent):
+    def __init__(self, text_edit):
         """ Create a call tip manager that is attached to the specified Qt
             text edit widget.
         """
-        assert isinstance(parent, (QtGui.QTextEdit, QtGui.QPlainTextEdit))
-        QtCore.QObject.__init__(self, parent)
+        assert isinstance(text_edit, (QtGui.QTextEdit, QtGui.QPlainTextEdit))
+        super(BracketMatcher, self).__init__()
 
         # The format to apply to matching brackets.
         self.format = QtGui.QTextCharFormat()
         self.format.setBackground(QtGui.QColor('silver'))
 
-        parent.cursorPositionChanged.connect(self._cursor_position_changed)
+        self._text_edit = text_edit
+        text_edit.cursorPositionChanged.connect(self._cursor_position_changed)
 
     #--------------------------------------------------------------------------
     # Protected interface
@@ -40,7 +41,7 b' class BracketMatcher(QtCore.QObject):'
             position of the matching bracket. Returns -1 if unsuccessful.
         """
         # Decide what character to search for and what direction to search in.
-        document = self.parent().document()
+        document = self._text_edit.document()
         qchar = document.characterAt(position)
         start_char = qchar.toAscii()
         search_char = self._opening_map.get(start_char)
@@ -73,7 +74,7 b' class BracketMatcher(QtCore.QObject):'
         """ Convenience method for selecting a character.
         """
         selection = QtGui.QTextEdit.ExtraSelection()
-        cursor = self.parent().textCursor()
+        cursor = self._text_edit.textCursor()
         cursor.setPosition(position)
         cursor.movePosition(QtGui.QTextCursor.NextCharacter, 
                             QtGui.QTextCursor.KeepAnchor)
@@ -87,15 +88,14 b' class BracketMatcher(QtCore.QObject):'
         """ Updates the document formatting based on the new cursor position.
         """
         # Clear out the old formatting.
-        text_edit = self.parent()
-        text_edit.setExtraSelections([])
+        self._text_edit.setExtraSelections([])
 
         # Attempt to match a bracket for the new cursor position.
-        cursor = text_edit.textCursor()
+        cursor = self._text_edit.textCursor()
         if not cursor.hasSelection():
             position = cursor.position() - 1
             match_position = self._find_match(position)
             if match_position != -1:
                 extra_selections = [ self._selection_for_character(pos)
                                      for pos in (position, match_position) ]
-                text_edit.setExtraSelections(extra_selections)
+                self._text_edit.setExtraSelections(extra_selections)

IPython/frontend/qt/console/call_tip_widget.py

@@ -14,16 +14,17 b' class CallTipWidget(QtGui.QLabel):'
     # 'QObject' interface
     #--------------------------------------------------------------------------
 
-    def __init__(self, parent):
+    def __init__(self, text_edit):
         """ Create a call tip manager that is attached to the specified Qt
             text edit widget.
         """
-        assert isinstance(parent, (QtGui.QTextEdit, QtGui.QPlainTextEdit))
-        QtGui.QLabel.__init__(self, parent, QtCore.Qt.ToolTip)
+        assert isinstance(text_edit, (QtGui.QTextEdit, QtGui.QPlainTextEdit))
+        super(CallTipWidget, self).__init__(None, QtCore.Qt.ToolTip)
 
         self._hide_timer = QtCore.QBasicTimer()
+        self._text_edit = text_edit
 
-        self.setFont(parent.document().defaultFont())
+        self.setFont(text_edit.document().defaultFont())
         self.setForegroundRole(QtGui.QPalette.ToolTipText)
         self.setBackgroundRole(QtGui.QPalette.ToolTipBase)
         self.setPalette(QtGui.QToolTip.palette())
@@ -37,10 +38,10 b' class CallTipWidget(QtGui.QLabel):'
                 QtGui.QStyle.SH_ToolTipLabel_Opacity, None, self) / 255.0)
 
     def eventFilter(self, obj, event):
-        """ Reimplemented to hide on certain key presses and on parent focus
+        """ Reimplemented to hide on certain key presses and on text edit focus
             changes.
         """
-        if obj == self.parent():
+        if obj == self._text_edit:
             etype = event.type()
 
             if etype == QtCore.QEvent.KeyPress:
@@ -60,7 +61,7 b' class CallTipWidget(QtGui.QLabel):'
             elif etype == QtCore.QEvent.Leave:
                 self._hide_later()
 
-        return QtGui.QLabel.eventFilter(self, obj, event)
+        return super(CallTipWidget, self).eventFilter(obj, event)
 
     def timerEvent(self, event):
         """ Reimplemented to hide the widget when the hide timer fires.
@@ -76,21 +77,21 b' class CallTipWidget(QtGui.QLabel):'
     def enterEvent(self, event):
         """ Reimplemented to cancel the hide timer.
         """
-        QtGui.QLabel.enterEvent(self, event)
+        super(CallTipWidget, self).enterEvent(event)
         self._hide_timer.stop()
 
     def hideEvent(self, event):
         """ Reimplemented to disconnect signal handlers and event filter.
         """
-        QtGui.QLabel.hideEvent(self, event)
-        parent = self.parent()
-        parent.cursorPositionChanged.disconnect(self._cursor_position_changed)
-        parent.removeEventFilter(self)
+        super(CallTipWidget, self).hideEvent(event)
+        self._text_edit.cursorPositionChanged.disconnect(
+            self._cursor_position_changed)
+        self._text_edit.removeEventFilter(self)
 
     def leaveEvent(self, event):
         """ Reimplemented to start the hide timer.
         """
-        QtGui.QLabel.leaveEvent(self, event)
+        super(CallTipWidget, self).leaveEvent(event)
         self._hide_later()
 
     def paintEvent(self, event):
@@ -102,15 +103,15 b' class CallTipWidget(QtGui.QLabel):'
         painter.drawPrimitive(QtGui.QStyle.PE_PanelTipLabel, option)
         painter.end()
 
-        QtGui.QLabel.paintEvent(self, event)
+        super(CallTipWidget, self).paintEvent(event)
 
     def showEvent(self, event):
         """ Reimplemented to connect signal handlers and event filter.
         """
-        QtGui.QLabel.showEvent(self, event)
-        parent = self.parent()
-        parent.cursorPositionChanged.connect(self._cursor_position_changed)
-        parent.installEventFilter(self)
+        super(CallTipWidget, self).showEvent(event)
+        self._text_edit.cursorPositionChanged.connect(
+            self._cursor_position_changed)
+        self._text_edit.installEventFilter(self)
 
     #--------------------------------------------------------------------------
     # 'CallTipWidget' interface
@@ -131,7 +132,7 b' class CallTipWidget(QtGui.QLabel):'
         """ Attempts to show the specified tip at the current cursor location.
         """
         # Attempt to find the cursor position at which to show the call tip.
-        text_edit = self.parent()
+        text_edit = self._text_edit
         document = text_edit.document()
         cursor = text_edit.textCursor()
         search_pos = cursor.position() - 1
@@ -172,7 +173,7 b' class CallTipWidget(QtGui.QLabel):'
             not found) and the number commas (at depth 0) found along the way.
         """
         commas = depth = 0
-        document = self.parent().document()
+        document = self._text_edit.document()
         qchar = document.characterAt(position)
         while (position > 0 and qchar.isPrint() and 
                # Need to check explicitly for line/paragraph separators:
@@ -205,7 +206,7 b' class CallTipWidget(QtGui.QLabel):'
     def _cursor_position_changed(self):
         """ Updates the tip based on user cursor movement.
         """
-        cursor = self.parent().textCursor()
+        cursor = self._text_edit.textCursor()
         if cursor.position() <= self._start_position:
             self.hide()
         else:

IPython/frontend/qt/console/completion_widget.py

@@ -10,18 +10,20 b' class CompletionWidget(QtGui.QListWidget):'
     # 'QObject' interface
     #--------------------------------------------------------------------------
 
-    def __init__(self, parent):
+    def __init__(self, text_edit):
         """ Create a completion widget that is attached to the specified Qt
             text edit widget.
         """
-        assert isinstance(parent, (QtGui.QTextEdit, QtGui.QPlainTextEdit))
-        QtGui.QListWidget.__init__(self, parent)
+        assert isinstance(text_edit, (QtGui.QTextEdit, QtGui.QPlainTextEdit))
+        super(CompletionWidget, self).__init__()
+
+        self._text_edit = text_edit
 
-        self.setWindowFlags(QtCore.Qt.ToolTip | QtCore.Qt.WindowStaysOnTopHint)
         self.setAttribute(QtCore.Qt.WA_StaticContents)
+        self.setWindowFlags(QtCore.Qt.ToolTip | QtCore.Qt.WindowStaysOnTopHint)
 
-        # Ensure that parent keeps focus when widget is displayed.
-        self.setFocusProxy(parent)
+        # Ensure that the text edit keeps focus when widget is displayed.
+        self.setFocusProxy(self._text_edit)
 
         self.setFrameShadow(QtGui.QFrame.Plain)
         self.setFrameShape(QtGui.QFrame.StyledPanel)
@@ -29,10 +31,10 b' class CompletionWidget(QtGui.QListWidget):'
         self.itemActivated.connect(self._complete_current)
 
     def eventFilter(self, obj, event):
-        """ Reimplemented to handle keyboard input and to auto-hide when our
-            parent loses focus.
+        """ Reimplemented to handle keyboard input and to auto-hide when the
+            text edit loses focus.
         """
-        if obj == self.parent():
+        if obj == self._text_edit:
             etype = event.type()
 
             if etype == QtCore.QEvent.KeyPress:
@@ -47,13 +49,13 b' class CompletionWidget(QtGui.QListWidget):'
                 elif key in (QtCore.Qt.Key_Up, QtCore.Qt.Key_Down, 
                              QtCore.Qt.Key_PageUp, QtCore.Qt.Key_PageDown, 
                              QtCore.Qt.Key_Home, QtCore.Qt.Key_End):
-                    QtGui.QListWidget.keyPressEvent(self, event)
+                    self.keyPressEvent(event)
                     return True
 
             elif etype == QtCore.QEvent.FocusOut:
                 self.hide()
 
-        return QtGui.QListWidget.eventFilter(self, obj, event)
+        return super(CompletionWidget, self).eventFilter(obj, event)
 
     #--------------------------------------------------------------------------
     # 'QWidget' interface
@@ -62,21 +64,16 b' class CompletionWidget(QtGui.QListWidget):'
     def hideEvent(self, event):
         """ Reimplemented to disconnect signal handlers and event filter.
         """
-        QtGui.QListWidget.hideEvent(self, event)
-        parent = self.parent()
-        try:
-            parent.cursorPositionChanged.disconnect(self._update_current)
-        except TypeError:
-            pass
-        parent.removeEventFilter(self)
+        super(CompletionWidget, self).hideEvent(event)
+        self._text_edit.cursorPositionChanged.disconnect(self._update_current)
+        self._text_edit.removeEventFilter(self)
 
     def showEvent(self, event):
         """ Reimplemented to connect signal handlers and event filter.
         """
-        QtGui.QListWidget.showEvent(self, event)
-        parent = self.parent()
-        parent.cursorPositionChanged.connect(self._update_current)
-        parent.installEventFilter(self)
+        super(CompletionWidget, self).showEvent(event)
+        self._text_edit.cursorPositionChanged.connect(self._update_current)
+        self._text_edit.installEventFilter(self)
 
     #--------------------------------------------------------------------------
     # 'CompletionWidget' interface
@@ -86,7 +83,7 b' class CompletionWidget(QtGui.QListWidget):'
         """ Shows the completion widget with 'items' at the position specified
             by 'cursor'.
         """
-        text_edit = self.parent()
+        text_edit = self._text_edit
         point = text_edit.cursorRect(cursor).bottomRight()
         point = text_edit.mapToGlobal(point)
         screen_rect = QtGui.QApplication.desktop().availableGeometry(self)
@@ -115,7 +112,7 b' class CompletionWidget(QtGui.QListWidget):'
         """ Returns a cursor with text between the start position and the
             current position selected.
         """
-        cursor = self.parent().textCursor()
+        cursor = self._text_edit.textCursor()
         if cursor.position() >= self._start_position:
             cursor.setPosition(self._start_position, 
                                QtGui.QTextCursor.KeepAnchor)

IPython/frontend/qt/console/ipythonqt.py

@@ -46,13 +46,17 b' class MainWindow(QtGui.QMainWindow):'
     def closeEvent(self, event):
         """ Reimplemented to prompt the user and close the kernel cleanly.
         """
-        reply = QtGui.QMessageBox.question(self, self.window().windowTitle(),
-            'Close console?', QtGui.QMessageBox.Yes, QtGui.QMessageBox.No)
-        if reply == QtGui.QMessageBox.Yes:
-            self._frontend.kernel_manager.shutdown_kernel()
-            event.accept()
-        else:
-            event.ignore()
+        kernel_manager = self._frontend.kernel_manager
+        if kernel_manager and kernel_manager.channels_running:
+            title = self.window().windowTitle()
+            reply = QtGui.QMessageBox.question(self, title,
+                'Close console?', QtGui.QMessageBox.Yes, QtGui.QMessageBox.No)
+            if reply == QtGui.QMessageBox.Yes:
+                kernel_manager.shutdown_kernel()
+                #kernel_manager.stop_channels()
+                event.accept()
+            else:
+                event.ignore()
 
 #-----------------------------------------------------------------------------
 # Main entry point