clone cms with menus, make menus standalone app

cms/models/settingmodels.py

@@ -0,0 +1,46 @@
+from django.conf import settings
+from django.db import models
+from django.utils.encoding import force_str
+from django.utils.translation import gettext_lazy as _
+
+
+class PlaceholderForeignKey(models.ForeignKey):
+    def run_checks(self, placeholder, user):
+        # A clipboard is private to its owner: only they have permission to
+        # change it. Other users must not be able to read from or write to it.
+        try:
+            return placeholder.source.has_placeholder_change_permission(user)
+        except AttributeError:
+            return False
+
+
+class UserSettings(models.Model):
+    user = models.OneToOneField(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        editable=False,
+        related_name='djangocms_usersettings',
+    )
+    language = models.CharField(_("Language"), max_length=10, choices=settings.LANGUAGES,
+                                help_text=_("The language for the admin interface and toolbar"))
+    clipboard = PlaceholderForeignKey(
+        'cms.Placeholder',
+        on_delete=models.CASCADE,
+        blank=True,
+        null=True,
+        editable=False,
+    )
+
+    class Meta:
+        verbose_name = _('user setting')
+        verbose_name_plural = _('user settings')
+        app_label = 'cms'
+
+    def __str__(self):
+        return force_str(self.user)
+
+    def has_placeholder_change_permission(self, user):
+        # User always has permission to change their own clipboard, but only
+        # their own: a clipboard may contain content other users are not
+        # allowed to see.
+        return self.user_id == user.pk or user.is_superuser