@@ -60,7 +60,7 @@ Shortcuts:

     options = parser.parse_args()

     inputfile = options.inputfile

-    width = height = 512

+    width, height = 610, 610

     if options.geometry:

         try:

             width, height = (int(i) for i in options.geometry.split('x'))

@@ -50,7 +50,8 @@ class DotWidget(Gtk.DrawingArea):

     # TODO GTK3: Second argument has to be of type Gdk.EventButton instead of object.

     __gsignals__ = {

         'clicked': (GObject.SIGNAL_RUN_LAST, None, (str, object)),

-        'error': (GObject.SIGNAL_RUN_LAST, None, (str,))

+        'error': (GObject.SIGNAL_RUN_LAST, None, (str,)),

+        'history': (GObject.SIGNAL_RUN_LAST, None, (bool, bool))

     }

     filter = 'dot'

@@ -89,6 +90,8 @@ class DotWidget(Gtk.DrawingArea):

         self.presstime = None

         self.highlight = None

         self.highlight_search = False

+        self.history_back = []

+        self.history_forward = []

     def error_dialog(self, message):

         self.emit('error', message)

@@ -160,6 +163,8 @@ class DotWidget(Gtk.DrawingArea):

                 fp.close()

             except IOError:

                 pass

+            else:

+                del self.history_back[:], self.history_forward[:]

     def update(self):

         if self.openfilename is not None:

@@ -439,9 +444,39 @@ class DotWidget(Gtk.DrawingArea):

             self.zoom_to_fit()

     def animate_to(self, x, y):

+        del self.history_forward[:]

+        self.history_back.append(self.get_current_pos())

+        self.history_changed()

+        self._animate_to(x, y)

+

+    def _animate_to(self, x, y):

         self.animation = animation.ZoomToAnimation(self, x, y)

         self.animation.start()

+    def history_changed(self):

+        self.emit(

+            'history',

+            bool(self.history_back),

+            bool(self.history_forward))

+

+    def on_go_back(self, action=None):

+        try:

+            item = self.history_back.pop()

+        except LookupError:

+            return

+        self.history_forward.append(self.get_current_pos())

+        self.history_changed()

+        self._animate_to(*item)

+

+    def on_go_forward(self, action=None):

+        try:

+            item = self.history_forward.pop()

+        except LookupError:

+            return

+        self.history_back.append(self.get_current_pos())

+        self.history_changed()

+        self._animate_to(*item)

+

     def window2graph(self, x, y):

         rect = self.get_allocation()

         x -= 0.5*rect.width

@@ -481,6 +516,9 @@ class DotWindow(Gtk.Window):

             <toolitem action="Reload"/>

             <toolitem action="Print"/>

             <separator/>

+            <toolitem action="Back"/>

+            <toolitem action="Forward"/>

+            <separator/>

             <toolitem action="ZoomIn"/>

             <toolitem action="ZoomOut"/>

             <toolitem action="ZoomFit"/>

@@ -507,6 +545,7 @@ class DotWindow(Gtk.Window):

         self.dotwidget = widget or DotWidget()

         self.dotwidget.connect("error", lambda e, m: self.error_dialog(m))

+        self.dotwidget.connect("history", self.on_history)

         # Create a UIManager instance

         uimanager = self.uimanager = Gtk.UIManager()

@@ -531,6 +570,16 @@ class DotWindow(Gtk.Window):

             ('Zoom100', Gtk.STOCK_ZOOM_100, None, None, None, self.dotwidget.on_zoom_100),

         ))

+        self.back_action = Gtk.Action('Back', None, None, Gtk.STOCK_GO_BACK)

+        self.back_action.set_sensitive(False)

+        self.back_action.connect("activate", self.dotwidget.on_go_back)

+        actiongroup.add_action(self.back_action)

+

+        self.forward_action = Gtk.Action('Forward', None, None, Gtk.STOCK_GO_FORWARD)

+        self.forward_action.set_sensitive(False)

+        self.forward_action.connect("activate", self.dotwidget.on_go_forward)

+        actiongroup.add_action(self.forward_action)

+

         find_action = FindMenuToolAction("Find", None,

                                          "Find a node by name", None)

         actiongroup.add_action(find_action)

@@ -658,3 +707,7 @@ class DotWindow(Gtk.Window):

         dlg.set_title(self.base_title)

         dlg.run()

         dlg.destroy()

+

+    def on_history(self, action, has_back, has_forward):

+        self.back_action.set_sensitive(has_back)

+        self.forward_action.set_sensitive(has_forward)