[meld] linkmap: Fix for 3.20, where GtkDrawingArea doesn't draw the background

[Kai Willadsen <kaiw src gnome org>]

commit 68a7f0ee5f615143d2c90e6835c1432f096575a9
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Thu Feb 11 07:14:02 2016 +1000

    linkmap: Fix for 3.20, where GtkDrawingArea doesn't draw the background
    
    According to bug #761341, this is the expected fix.

 meld/linkmap.py |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/meld/linkmap.py b/meld/linkmap.py
index 47b3dea..c50b50a 100644
--- a/meld/linkmap.py
+++ b/meld/linkmap.py
@@ -64,6 +64,10 @@ class LinkMap(Gtk.DrawingArea):
         context.rectangle(0, clip_y, allocation.width, clip_height)
         context.clip()
 
+        stylecontext = self.get_style_context()
+        Gtk.render_background(
+            stylecontext, context, 0, clip_y, allocation.width, clip_height)
+
         height = allocation.height
         visible = [self.views[0].get_line_num_for_y(pix_start[0]),
                    self.views[0].get_line_num_for_y(pix_start[0] + height),