[gnome-tweak-tool] Revert "appearance: Stop requiring gtk2 version of theme"

[Jeremy Bicha <jbicha src gnome org>]

commit de86413d4bedd04f2e7e3033f448671fd94faddb
Author: Jeremy Bicha <jbicha ubuntu com>
Date:   Fri Nov 3 14:28:55 2017 -0400

    Revert "appearance: Stop requiring gtk2 version of theme"
    
    This reverts commit 8815013c5eee812fd416a7a511c8a7086d5dce06.

 gtweak/tweaks/tweak_group_appearance.py |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/gtweak/tweaks/tweak_group_appearance.py b/gtweak/tweaks/tweak_group_appearance.py
index ee12b75..7380c47 100644
--- a/gtweak/tweaks/tweak_group_appearance.py
+++ b/gtweak/tweaks/tweak_group_appearance.py
@@ -45,13 +45,17 @@ class GtkThemeSwitcher(GSettingsComboTweak):
             **options)
 
     def _get_valid_themes(self):
-        """ Only shows themes that have variations for gtk3"""
+        """ Only shows themes that have variations for gtk+-3 and gtk+-2 """
+        gtk_ver = Gtk.MINOR_VERSION
+        if gtk_ver % 2: # Want even number
+            gtk_ver += 1
 
         dirs = ( os.path.join(gtweak.DATA_DIR, "themes"),
                  os.path.join(GLib.get_user_data_dir(), "themes"),
                  os.path.join(os.path.expanduser("~"), ".themes"))
         valid = walk_directories(dirs, lambda d:
-                    os.path.exists(os.path.join(d, "gtk-3.0")) or \
+                    os.path.exists(os.path.join(d, "gtk-2.0")) and \
+                        (os.path.exists(os.path.join(d, "gtk-3.0")) or \
                          os.path.exists(os.path.join(d, "gtk-3.{}".format(gtk_ver)))))
 
         if 'Adwaita' not in valid: