Set value on focus out for calendar widgets

We can not rely only on *-changed events to set the value because if the user
has typed the date in the exact format, the date-time widgets do not emit a
*-changed event.

issue11815
review425961003
(grafted from 137038265d959e4e41a7c5e7da0db14e93f47e0a)

--HG--
branch : 6.0

tryton/gui/window/view_form/view/form_gtk/calendar_.py

@@ -25,6 +25,8 @@ class Date(Widget):
         self.real_entry.connect('key_press_event', self.sig_key_press)
         self.real_entry.connect('activate', self.sig_activate)
         self.real_entry.connect('changed', lambda _: self.send_modified())
+        self.real_entry.connect(
+            'focus-out-event', lambda *a: self._focus_out())
         self.entry.connect(self._changed_signal, self.changed)
         self.widget.pack_start(self.entry, expand=False, fill=False, padding=0)