[pitivi] timeline: Fix the background color of the scrollbars

[Alexandru Băluț <alexbalut src gnome org>]

commit 5ea69f6f9cd55d4d163b22074c510c21f4c1c8e6
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Wed Oct 5 01:54:41 2016 +0200

    timeline: Fix the background color of the scrollbars
    
    Until now it was darker than the background of the timeline, now it's
    the same.
    
    Reviewed-by: Thibault Saunier <tsaunier gnome org>
    Differential Revision: https://phabricator.freedesktop.org/D1348

 pitivi/timeline/timeline.py |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)
---
diff --git a/pitivi/timeline/timeline.py b/pitivi/timeline/timeline.py
index ec2265f..e9aebb9 100644
--- a/pitivi/timeline/timeline.py
+++ b/pitivi/timeline/timeline.py
@@ -1336,7 +1336,9 @@ class TimelineContainer(Gtk.Grid, Zoomable, Loggable):
         self.vadj = self.timeline.layout.get_vadjustment()
 
         vscrollbar = Gtk.VScrollbar(adjustment=self.vadj)
+        vscrollbar.get_style_context().add_class("background")
         hscrollbar = Gtk.HScrollbar(adjustment=self.hadj)
+        hscrollbar.get_style_context().add_class("background")
 
         self.ruler = ScaleRuler(self, self.hadj)
         self.ruler.props.hexpand = True
@@ -1352,13 +1354,6 @@ class TimelineContainer(Gtk.Grid, Zoomable, Loggable):
         self.gapless_button = builder.get_object("gapless_button")
         self.gapless_button.set_active(self._autoripple_active)
 
-        alter_style_class(
-            ".%s.trough" % Gtk.STYLE_CLASS_SCROLLBAR, vscrollbar,
-            "border: alpha (@base_color, 0.0); background: alpha (@base_color, 0.0);")
-        alter_style_class(
-            ".%s.trough" % Gtk.STYLE_CLASS_SCROLLBAR, hscrollbar,
-            "border: alpha (@base_color, 0.0); background: alpha (@base_color, 0.0);")
-
         self.attach(zoom_box, 0, 0, 1, 1)
         self.attach(self.ruler, 1, 0, 1, 1)
         self.attach(self.timeline, 0, 1, 2, 1)