[meld] bin/meld: Work-around for GTK+ 3.14 background drawing, part 2

[Kai Willadsen <kaiw src gnome org>]

commit f9c4e540385adfb5c22b8d747c0e2a8fc42ffe37
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sat Oct 25 10:55:22 2014 +1000

    bin/meld: Work-around for GTK+ 3.14 background drawing, part 2
    
    Commit 61f53b0c reset the drawn background to transparent, which works
    for most drawing, but looks terrible as soon as any text is selected.
    
    This commit adds a secondary horrible hack that tries to reproduce the
    selected text background colour once we've reset the main widget
    background. This does use a horrible undocumented internal CSS class
    that GtkTextView applies when rendering text, but it's the only way
    that I could find that should hopefully work across different themes.

 bin/meld |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)
---
diff --git a/bin/meld b/bin/meld
index 5ca3344..9e7394a 100755
--- a/bin/meld
+++ b/bin/meld
@@ -196,9 +196,20 @@ def setup_resources():
         Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION)
 
     if Gtk.get_minor_version() >= 13:
+        # Retrieve the selection colour from GtkTextView. Ideally, we'd do this
+        # on MeldSourceView, but we don't really want to import that here.
+        style = Gtk.StyleContext()
+        widget_path = Gtk.WidgetPath()
+        widget_path.append_type(Gtk.TextView)
+        style.set_path(widget_path)
+        # This is basically indefensible internal GTK+ ABI, but... whatever.
+        style.add_class(Gtk.STYLE_CLASS_VIEW)
+        color = style.get_background_color(Gtk.StateFlags.SELECTED).to_string()
+
         fixes_provider = Gtk.CssProvider()
         fixes_provider.load_from_data(
-            "MeldSourceView { background-color: rgba(0.0, 0.0, 0.0, 0.0); }")
+            "MeldSourceView { background-color: rgba(0.0, 0.0, 0.0, 0.0); } "
+            "MeldSourceView:selected { background-color: %s; } " % color)
         Gtk.StyleContext.add_provider_for_screen(
             Gdk.Screen.get_default(), fixes_provider,
             Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION)