Show the xml parsing error if it encounters it, so the user can

double check the output the next time they run the dialog and
click the gear icon so they can fix the code in their pipemenu
scripts.

new-editor/cb-editor

@@ -255,9 +255,25 @@ class CBEditor(gtk.Window):
 		if response==gtk.RESPONSE_ACCEPT:
 			process=subprocess.Popen(shlex.split(os.path.expanduser(input.entry.props.text)), \
 				stdout=subprocess.PIPE)
-			dummy_menu=etree.fromstring("<menu name='Dummy'>%s</menu>" % process.communicate()[0])
-			self.recursive_generate(widget, dummy_menu)
-		dialog.destroy()
+			try:
+				stdout = process.communicate()[0]
+				dummy_txt = "<menu name='Dummy'>{}</menu>".format(stdout)
+				dummy_menu=etree.fromstring("<menu name='Dummy'>{}</menu>".format(stdout))
+				self.recursive_generate(widget, dummy_menu)
+				dialog.destroy()
+			except etree.XMLSyntaxError as e:
+				message = gtk.MessageDialog(parent=self, flags=0, 
+				    type=gtk.MESSAGE_ERROR, 
+				    buttons=gtk.BUTTONS_OK, message_format=None)
+				msg = ("{}\n\nClick the gear icon in the dialog to check"
+				" pipe output.").format(e.msg)
+				message.set_markup(msg)
+				message.run()
+				message.destroy()
+			finally:
+				dialog.destroy()
+		else:
+			dialog.destroy()
 
 	def make_new_item(self, widget, element_type, nd=None, parent=None):
 		if element_type != 'Menu File':