[pitivi] viewer: Do not set a negative min_size

[Thibault Saunier <tsaunier src gnome org>]

commit 7d748c4ece63a942988a80c649e9fb54fc0b0aa1
Author: Thibault Saunier <tsaunier gnome org>
Date:   Mon Sep 21 19:02:15 2015 +0200

    viewer: Do not set a negative min_size
    
    It will crash when undocking the sink

 pitivi/viewer.py |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/pitivi/viewer.py b/pitivi/viewer.py
index 1448ebf..5a5577a 100644
--- a/pitivi/viewer.py
+++ b/pitivi/viewer.py
@@ -637,12 +637,12 @@ class ViewerWidget(Gtk.AspectFrame, Loggable):
     def do_get_preferred_width(self):
         # Do not let a chance for Gtk to choose video natural size
         # as we want to have full control
-        return -1, -1
+        return 0, 1
 
     def do_get_preferred_height(self):
         # Do not let a chance for Gtk to choose video natural size
         # as we want to have full control
-        return -1, -1
+        return 0, 1
 
 
 class PlayPauseButton(Gtk.Button, Loggable):