[pitivi] keyframes: fix annoying warnings.

[Thibault Saunier <tsaunier src gnome org>]

commit 5f70cd605c719fead8eb2b973bfa67bffa0af02f
Author: Mathieu Duponchelle <mathieu duponchelle opencreed com>
Date:   Tue May 19 20:59:14 2015 +0200

    keyframes: fix annoying warnings.
    
    Summary: They were innocuous but boring
    
    Reviewers: thiblahute
    
    Differential Revision: http://phabricator.freedesktop.org/D187

 pitivi/timeline/elements.py |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/pitivi/timeline/elements.py b/pitivi/timeline/elements.py
index 10aa0b7..7fb755f 100644
--- a/pitivi/timeline/elements.py
+++ b/pitivi/timeline/elements.py
@@ -109,6 +109,9 @@ class KeyframeCurve(FigureCanvas, Loggable):
 
         self.__keyframes = self.__ax.scatter([], [], marker='D', s=sizes,
                                              c=colors, zorder=2)
+
+        # matplotlib weirdness, simply here to avoid a warning ..
+        self.__keyframes.set_picker(True)
         self.__line = self.__ax.plot([], [],
                                      linewidth=1.0, zorder=1)[0]
         self.__updatePlots()
@@ -137,8 +140,9 @@ class KeyframeCurve(FigureCanvas, Loggable):
         for value in values:
             self.__line_xs.append(value.timestamp)
             self.__line_ys.append(value.value)
-            self.__ax.set_xlim(self.__line_xs[0], self.__line_xs[-1])
-            self.__ax.set_ylim(0.0, 1.0)
+
+        self.__ax.set_xlim(self.__line_xs[0], self.__line_xs[-1])
+        self.__ax.set_ylim(0.0, 1.0)
 
         arr = numpy.array((self.__line_xs, self.__line_ys))
         arr = arr.transpose()