Use set_default_size instead of set_size_request to allow resize smaller

tryton/gui/main.py

@@ -38,7 +38,7 @@ class Main(object):
         super(Main, self).__init__()
 
         self.window = gtk.Window()
-        self.window.set_size_request(900, 750)
+        self.window.set_default_size(900, 750)
         self.window.set_resizable(True)
         self.window.set_title('Tryton')
         self.window.set_icon(TRYTON_ICON)