repair zoom regression

qtgui/mainwindow.py

@@ -417,6 +417,10 @@ class MainWindow(TemplateMainWindow):
         self.ui.toolBar.addWidget(whatTypeOfUnit)
         spacer()
 
+    def zoom(self, scaleFactor:float):
+        pass
+    def stretchXCoordinates(self, factor):
+        pass
 
     def zoomUpperHalf(self, delta):
         """This is called from within the parts of the combined song editor.