Version details: Seen in 1.6.4 and 1.6.5

I am only able to choose items from Epiphany's menus a couple of times before
they stop working. The following are my actions, and the corresponding error
messages in the console:

1. Open a new window:

(epiphany:10037): Gdk-WARNING **: gdk_property_get(): length value has wrapped
in calculation (did you pass G_MAXLONG?)

2. Pull down a menu and choose a menu item (Help/About Epiphany in this case).
This action succeeds, but the following is printed when I chose the menu item:

(epiphany:10195): GLib-GObject-CRITICAL **: g_object_ref: assertion `G_IS_OBJECT
(object)' failed
(epiphany:10195): GLib-GObject-CRITICAL **: g_object_unref: assertion
`G_IS_OBJECT (object)' failed

I can usually choose two or three menu items in different menus before they all
stop working.

3. Pull down a menu:

(epiphany:10195): GLib-GObject-CRITICAL **: g_object_ref: assertion `G_IS_OBJECT
(object)' failed
(epiphany:10195): GLib-GObject-CRITICAL **: g_object_unref: assertion
`G_IS_OBJECT (object)' failed
(epiphany:10195): Gtk-CRITICAL **: gtk_window_group_add_window: assertion
`GTK_IS_WINDOW_GROUP (window_group)' failed

4. Choose a menu item:

(epiphany:10195): GLib-GObject-CRITICAL **: g_object_ref: assertion `G_IS_OBJECT
(object)' failed
(epiphany:10195): GLib-GObject-CRITICAL **: g_object_unref: assertion
`G_IS_OBJECT (object)' failed