@@ -562,6 +562,10 @@ class XDotAttrParser:

         return self.parser.transform(x, y)

+class GraphParseError(Exception):

+    pass

+

+

 class XDotParser:

     def __init__(self, xdotcode):

@@ -571,7 +575,7 @@ class XDotParser:

         graph = pydot.graph_from_dot_data(self.xdotcode)

         if graph.bb is None:

-            return Graph()

+            return GraphParseError()

         xmin, ymin, xmax, ymax = map(int, graph.bb.split(","))

@@ -876,7 +880,7 @@ class DotWidget(gtk.DrawingArea):

         self.presstime = None

         self.highlight = None

-    def set_dotcode(self, dotcode):

+    def set_dotcode(self, dotcode, filename='<stdin>'):

         p = subprocess.Popen(

             ['dot', '-Txdot'],

             stdin=subprocess.PIPE,

@@ -885,7 +889,15 @@ class DotWidget(gtk.DrawingArea):

             universal_newlines=True

         )

         xdotcode = p.communicate(dotcode)[0]

-        self.set_xdotcode(xdotcode)

+        try:

+            self.set_xdotcode(xdotcode)

+        except GraphParseError, e:

+            msg = "Could not parse %s, is it a valid dot file?" % filename

+            error_dlg = gtk.MessageDialog(type=gtk.MESSAGE_ERROR,

+                                          message_format=msg,

+                                          buttons=gtk.BUTTONS_OK)

+            error_dlg.run()

+            error_dlg.destroy()

     def set_xdotcode(self, xdotcode):

         #print xdotcode

@@ -1143,7 +1155,7 @@ class DotWindow(gtk.Window):

         # Add the actiongroup to the uimanager

         uimanager.insert_action_group(actiongroup, 0)

-        # Add a UI description

+        # Add a UI descrption

         uimanager.add_ui_from_string(self.ui)

         # Create a Toolbar

@@ -1156,13 +1168,13 @@ class DotWindow(gtk.Window):

         self.show_all()

-    def set_dotcode(self, dotcode):

-        self.widget.set_dotcode(dotcode)

+    def set_dotcode(self, dotcode, filename='<stdin>'):

+        self.widget.set_dotcode(dotcode, filename)

     def open_file(self, filename):

         try:

             fp = file(filename, 'rt')

-            self.set_dotcode(fp.read())

+            self.set_dotcode(fp.read(), filename)

             fp.close()

         except IOError:

             # TODO: show an error message