[ocrfeeder] Fix mousewheel zoom (bug 620212)

[Joaquim Manuel Pereira Rocha <jrocha src gnome org>]

commit a689bfeafe44e1fb8742f51a3708d55e7d57e33b
Author: Stefan Löffler <st loeffler gmail com>
Date:   Fri Jun 4 10:14:54 2010 +0200

    Fix mousewheel zoom (bug 620212)
    
    Test only if Ctrl is pressed when mousewheel is scrolled (allows for some other mod flags to be present)

 studio/customWidgets.py |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/studio/customWidgets.py b/studio/customWidgets.py
index daa3b58..c8e0014 100644
--- a/studio/customWidgets.py
+++ b/studio/customWidgets.py
@@ -314,13 +314,17 @@ class SelectableBoxesArea(goocanvas.Canvas):
             self.emit('dragged_box', item)
     
     def scrollEventCb(self, widget, event):
-        if event.state == gtk.gdk.CONTROL_MASK:
+        # Note: This catches all modifier combinations that use Ctrl. Add
+        #       further combinations _before_ for them to take precedence!
+        if event.state & gtk.gdk.CONTROL_MASK:
             if event.direction == gtk.gdk.SCROLL_UP or \
                event.direction == gtk.gdk.SCROLL_RIGHT:
                 self.zoom(0.05)
+                return True # we have handled the event - don't propagate to parent
             elif event.direction == gtk.gdk.SCROLL_DOWN or \
                  event.direction == gtk.gdk.SCROLL_LEFT:
                 self.zoom(-0.05)
+                return True # we have handled the event - don't propagate to parent
     
     def setAreaFillRgba(self, rgba):
         self.area_fill_rgba = rgba