[pitivi] previewers: Fix visible thumbnail calculation

[Thibault Saunier <tsaunier src gnome org>]

commit 9685397f14afd0d245919e971d24a9b23c5bbb8d
Author: Thibault Saunier <tsaunier gnome org>
Date:   Tue Dec 8 16:35:42 2015 +0100

    previewers: Fix visible thumbnail calculation
    
    Differential Revision: https://phabricator.freedesktop.org/D585

 pitivi/timeline/previewers.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/pitivi/timeline/previewers.py b/pitivi/timeline/previewers.py
index 6f09a45..2f85b1d 100644
--- a/pitivi/timeline/previewers.py
+++ b/pitivi/timeline/previewers.py
@@ -376,7 +376,7 @@ class VideoPreviewer(Gtk.Layout, PreviewGenerator, Zoomable, Loggable):
         thumb_duration = self._get_thumb_duration()
 
         element_left = self.pixelToNs(rect.x) + self.bElement.props.in_point
-        element_right = element_left + self.bElement.props.duration
+        element_right = element_left + self.pixelToNs(rect.width)
         element_left = quantize(element_left, thumb_duration)
 
         for current_time in range(element_left, element_right, thumb_duration):