Add missing padding when pack_start context widget

Without pygtkcompat, all arguments must be passed to Gtk methods.

issue8261

tryton/gui/window/view_form/screen/screen.py

@@ -119,7 +119,7 @@ class Screen(SignalEvent):
                 remove_bin(widget)
 
             self.screen_container.filter_vbox.pack_start(
-                context_widget, expand=False, fill=True)
+                context_widget, expand=False, fill=True, padding=0)
             self.screen_container.filter_vbox.reorder_child(
                 context_widget, 0)
             self.context_screen.widget.show()