Force a display when group cleared

We must ensure that a model is set on the treeview before the former one became
invalid. This is because set_model calls gtk_tree_model_unref_node using the
previous model.
So the display (which set the new model) can not be delayed.

issue8552
review283851002

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

@@ -404,8 +404,8 @@ class Screen(SignalEvent):
 
     def _group_cleared(self, group, signal):
         for view in self.views:
-            if hasattr(view, 'reload'):
-                view.reload = True
+            if view.view_type == 'tree':
+                view.display(force=True)
 
     def _group_list_changed(self, group, signal):
         for view in self.views:

tryton/gui/window/view_form/view/list.py

@@ -436,7 +436,6 @@ class ViewTree(View):
         self.children_field = children_field
         self.sum_widgets = []
         self.sum_box = Gtk.HBox()
-        self.reload = False
         self.treeview = None
         editable = xml.getAttribute('editable')
         if editable and not screen.readonly:
@@ -1007,10 +1006,10 @@ class ViewTree(View):
     def reset(self):
         pass
 
-    def display(self):
+    def display(self, force=False):
         self.treeview.display_counter += 1
         current_record = self.record
-        if (self.reload
+        if (force
                 or not self.treeview.get_model()
                 or self.group != self.treeview.get_model().group):
             model = AdaptModelGroup(self.group, self.children_field)
@@ -1021,7 +1020,6 @@ class ViewTree(View):
                 selection = self.treeview.get_selection()
                 path = current_record.get_index_path(model.group)
                 selection.select_path(path)
-        self.reload = False
         if not current_record:
             selection = self.treeview.get_selection()
             selection.unselect_all()