Add mouse scroll event/zoom on overview

gui/cadbiom_gui/gt_gui/charter.py

@@ -220,6 +220,8 @@ class Charter(object):
 
         # overview
         self.overview_window = self.wtree.get_widget("Overview")
+        self.overview_window.connect('scroll-event',
+                                     self.on_button_scroll_event)
 
 
     def check_curent_model(function):
@@ -370,6 +372,12 @@ class Charter(object):
         bhan = but.connect("clicked", self.current_edit_mvc.zoom_minus)
         self.button_handlers["zoom_m"] = (but, bhan)
 
+    def on_button_scroll_event(self, widget, event):
+        """Handle zoom based on mouse scroll event on the overview"""
+        if event.direction == gtk.gdk.SCROLL_UP:
+            self.current_edit_mvc.zoom_plus(widget)
+        elif event.direction == gtk.gdk.SCROLL_DOWN:
+            self.current_edit_mvc.zoom_minus(widget)
 
     def add_image(self, widget, image_file):
         """Add image to a Button