[pygobject/pygobject-3-10] Fix TypeError when setting drag target_list to None

[Martin Pitt <martinpitt src gnome org>]

commit 43ac1f9fd4b1f5132b7fa996da7e307371d11bb1
Author: Nuno Araujo <nuno araujo russo79 com>
Date:   Fri Oct 11 18:41:48 2013 +0200

    Fix TypeError when setting drag target_list to None
    
    When calling Widget.drag_dest_set_target_list(None) or Widget.drag_source_set_target_list(None)
    a "TypeError: 'NoneType' object is not iterable" is thrown.
    
    According to Gtk documentation [1] [2], this shouldn't be the case since client code should be
    able to pass NULL in calls made to gtk_drag_dest_set_target_list and
    gtk_drag_source_set_target_list.
    
    We now check if the target_list is None and do not try to create a TargetList if it is the case.
    
    [1] https://developer.gnome.org/gtk3/3.10/gtk3-Drag-and-Drop.html#gtk-drag-dest-set-target-list
    [2] https://developer.gnome.org/gtk3/3.10/gtk3-Drag-and-Drop.html#gtk-drag-source-set-target-list
    
    https://bugzilla.gnome.org/show_bug.cgi?id=709926

 gi/overrides/Gtk.py         |    4 ++--
 tests/test_overrides_gtk.py |    2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/gi/overrides/Gtk.py b/gi/overrides/Gtk.py
index 5899596..e774c0c 100644
--- a/gi/overrides/Gtk.py
+++ b/gi/overrides/Gtk.py
@@ -73,12 +73,12 @@ class Widget(Gtk.Widget):
         return super(Widget, self).render_icon(stock_id, size, detail)
 
     def drag_dest_set_target_list(self, target_list):
-        if not isinstance(target_list, Gtk.TargetList):
+        if (target_list is not None) and (not isinstance(target_list, Gtk.TargetList)):
             target_list = Gtk.TargetList.new(_construct_target_list(target_list))
         super(Widget, self).drag_dest_set_target_list(target_list)
 
     def drag_source_set_target_list(self, target_list):
-        if not isinstance(target_list, Gtk.TargetList):
+        if (target_list is not None) and (not isinstance(target_list, Gtk.TargetList)):
             target_list = Gtk.TargetList.new(_construct_target_list(target_list))
         super(Widget, self).drag_source_set_target_list(target_list)
 
diff --git a/tests/test_overrides_gtk.py b/tests/test_overrides_gtk.py
index fbe51ec..fd97908 100644
--- a/tests/test_overrides_gtk.py
+++ b/tests/test_overrides_gtk.py
@@ -464,6 +464,7 @@ class TestGtk(unittest.TestCase):
         widget.drag_dest_get_track_motion()
         widget.drag_dest_set_track_motion(True)
         widget.drag_dest_get_target_list()
+        widget.drag_dest_set_target_list(None)
         widget.drag_dest_set_target_list(Gtk.TargetList.new([Gtk.TargetEntry.new('test', 0, 0)]))
         widget.drag_dest_unset()
 
@@ -479,6 +480,7 @@ class TestGtk(unittest.TestCase):
         widget.drag_source_set_icon_pixbuf(GdkPixbuf.Pixbuf())
         widget.drag_source_set_icon_stock("")
         widget.drag_source_get_target_list()
+        widget.drag_source_set_target_list(None)
         widget.drag_source_set_target_list(Gtk.TargetList.new([Gtk.TargetEntry.new('test', 0, 0)]))
         widget.drag_source_unset()