Allow running with olddb

src/calibre/gui2/library/alternate_views.py

@@ -538,6 +538,8 @@ class GridView(QListView):
         self.delegate.render_queue.put(None)
 
     def set_database(self, newdb, stage=0):
+        if not hasattr(newdb, 'new_api'):
+            return
         if stage == 0:
             self.ignore_render_requests.set()
             try:

src/calibre/gui2/preferences/look_feel.py

@@ -13,7 +13,7 @@ from calibre.gui2.preferences.look_feel_ui import Ui_Form
 from calibre.gui2 import config, gprefs, qt_app, NONE
 from calibre.utils.localization import (available_translations,
     get_language, get_lang)
-from calibre.utils.config import prefs
+from calibre.utils.config import prefs, tweaks
 from calibre.utils.icu import sort_key
 from calibre.gui2.book_details import get_field_list
 from calibre.gui2.preferences.coloring import EditRules
@@ -200,6 +200,10 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         self.fs_help_msg.setText(unicode(self.fs_help_msg.text())%(
             _(' or ').join(keys)))
         self.cover_grid_color_button.clicked.connect(self.change_cover_grid_color)
+        if not tweaks.get('use_new_db', False):
+            for i in range(self.tabWidget.count()):
+                if self.tabWidget.widget(i) is self.cover_grid_tab:
+                    self.tabWidget.removeTab(i)
 
     def initialize(self):
         ConfigWidgetBase.initialize(self)

src/calibre/gui2/preferences/look_feel.ui

@@ -223,7 +223,7 @@
        </item>
       </layout>
      </widget>
-     <widget class="QWidget" name="tab_5">
+     <widget class="QWidget" name="cover_grid_tab">
       <attribute name="icon">
        <iconset resource="../../../../resources/images.qrc">
         <normaloff>:/images/grid.png</normaloff>:/images/grid.png</iconset>