diff --git a/src/calibre/gui2/preferences/__init__.py b/src/calibre/gui2/preferences/__init__.py
index 045d7ceebb..b9614bcf8c 100644
--- a/src/calibre/gui2/preferences/__init__.py
+++ b/src/calibre/gui2/preferences/__init__.py
@@ -18,6 +18,11 @@ class AbortCommit(Exception):
 
 class ConfigWidgetInterface(object):
 
+    '''
+    This class defines the interface that all widgets displayed in the
+    Preferences dialog must implement. To create a plugin for a new
+    '''
+
     changed_signal = None
     supports_restoring_to_defaults = True
     restore_defaults_desc = _('Restore settings to default values. '
diff --git a/src/calibre/gui2/preferences/main.py b/src/calibre/gui2/preferences/main.py
index d55f2d90d1..f6a20d74d9 100644
--- a/src/calibre/gui2/preferences/main.py
+++ b/src/calibre/gui2/preferences/main.py
@@ -13,7 +13,7 @@ from PyQt4.Qt import QMainWindow, Qt, QIcon, QStatusBar, QFont, QWidget, \
         QToolBar, QSize, pyqtSignal, QPixmap, QToolButton, QAction, \
         QDialogButtonBox, QHBoxLayout
 
-from calibre.constants import __appname__, __version__, islinux, isosx
+from calibre.constants import __appname__, __version__, islinux
 from calibre.gui2 import gprefs, min_available_height, available_width, \
     warning_dialog
 from calibre.gui2.preferences import init_gui, AbortCommit, get_plugin
@@ -164,7 +164,7 @@ class Preferences(QMainWindow):
         self.must_restart = False
         self.committed = False
 
-        self.resize(900, 760 if isosx else 710)
+        self.resize(900, 720)
         nh, nw = min_available_height()-25, available_width()-10
         if nh < 0:
             nh = 800
@@ -201,7 +201,6 @@ class Preferences(QMainWindow):
         self.cw.layout().addWidget(self.bb)
         self.bb.rejected.connect(self.close, type=Qt.QueuedConnection)
         self.setCentralWidget(self.cw)
-        self.bb.setVisible(isosx)
         self.browser = Browser(self)
         self.browser.show_plugin.connect(self.show_plugin)
         self.stack.addWidget(self.browser)
diff --git a/src/calibre/manual/plugins.rst b/src/calibre/manual/plugins.rst
index 8b6919db90..3aca648a23 100644
--- a/src/calibre/manual/plugins.rst
+++ b/src/calibre/manual/plugins.rst
@@ -165,3 +165,11 @@ User Interface Actions
    :members:
    :member-order: bysource
 
+Preferences Plugins
+--------------------------
+
+.. autoclass:: calibre.customize.PreferencesPlugin
+   :show-inheritance:
+   :members:
+   :member-order: bysource
+