Add a new 'Calibre style' interface in case you are tired of the system default look. You can select it via Preferences->Look & Feel->User interface style.

src/calibre/gui2/__init__.py

@@ -8,7 +8,7 @@ from PyQt4.Qt import (QVariant, QFileInfo, QObject, SIGNAL, QBuffer, Qt,
                     QByteArray, QTranslator, QCoreApplication, QThread,
                     QEvent, QTimer, pyqtSignal, QDateTime, QDesktopServices,
                     QFileDialog, QFileIconProvider, QSettings,
-                    QIcon, QApplication, QDialog, QUrl, QFont)
+                    QIcon, QApplication, QDialog, QUrl, QFont, QPalette)
 
 ORG_NAME = 'KovidsBrain'
 APP_UID  = 'libprs500'
@@ -106,6 +106,7 @@ gprefs.defaults['auto_add_path'] = None
 gprefs.defaults['auto_add_check_for_duplicates'] = False
 gprefs.defaults['blocked_auto_formats'] = []
 gprefs.defaults['auto_add_auto_convert'] = True
+gprefs.defaults['widget_style'] = 'system'
 # }}}
 
 NONE = QVariant() #: Null value to return from the data function of item models
@@ -737,17 +738,26 @@ class Application(QApplication):
             if s is not None:
                 font.setStretch(s)
             QApplication.setFont(font)
-        st = self.style()
+        self.setup_styles()
-        if st is not None:
+
-            st = unicode(st.objectName()).lower()
+    def setup_styles(self):
-        if (islinux or isbsd) and st in ('windows', 'motif', 'cde'):
+        if gprefs['widget_style'] != 'system':
-            from PyQt4.Qt import QStyleFactory
+            # On OS X QtCurve resets the palette, so we preserve it explicitly
-            styles = set(map(unicode, QStyleFactory.keys()))
+            orig_pal = QPalette(self.palette())
-            if 'Plastique' in styles and os.environ.get('KDE_FULL_SESSION',
+            QApplication.setStyle('QtCurve')
-                    False):
+            self.setPalette(orig_pal)
-                self.setStyle('Plastique')
+        else:
-            elif 'Cleanlooks' in styles:
+            st = self.style()
-                self.setStyle('Cleanlooks')
+            if st is not None:
+                st = unicode(st.objectName()).lower()
+            if (islinux or isbsd) and st in ('windows', 'motif', 'cde'):
+                from PyQt4.Qt import QStyleFactory
+                styles = set(map(unicode, QStyleFactory.keys()))
+                if 'Plastique' in styles and os.environ.get('KDE_FULL_SESSION',
+                        False):
+                    self.setStyle('Plastique')
+                elif 'Cleanlooks' in styles:
+                    self.setStyle('Cleanlooks')
 
     def _send_file_open_events(self):
         with self._file_open_lock:

src/calibre/gui2/preferences/look_feel.py

@@ -101,6 +101,9 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
 
         r('gui_layout', config, restart_required=True, choices=
                 [(_('Wide'), 'wide'), (_('Narrow'), 'narrow')])
+        r('widget_style', gprefs, restart_required=True, choices=
+                [(_('System default'), 'system'), (_('Calibre style'),
+                    'calibre')])
 
         r('cover_flow_queue_length', config, restart_required=True)
 

src/calibre/gui2/preferences/look_feel.ui

@@ -28,7 +28,34 @@
        <string>Main Interface</string>
       </attribute>
       <layout class="QGridLayout" name="gridLayout_9">
-       <item row="0" column="0">
+       <item row="2" column="0">
+        <widget class="QLabel" name="label_7">
+         <property name="text">
+          <string>Choose &amp;language (requires restart):</string>
+         </property>
+         <property name="buddy">
+          <cstring>opt_language</cstring>
+         </property>
+        </widget>
+       </item>
+       <item row="2" column="1">
+        <widget class="QComboBox" name="opt_language">
+         <property name="sizeAdjustPolicy">
+          <enum>QComboBox::AdjustToMinimumContentsLengthWithIcon</enum>
+         </property>
+         <property name="minimumContentsLength">
+          <number>20</number>
+         </property>
+        </widget>
+       </item>
+       <item row="3" column="0">
+        <widget class="QCheckBox" name="opt_systray_icon">
+         <property name="text">
+          <string>Enable system &amp;tray icon (needs restart)</string>
+         </property>
+        </widget>
+       </item>
+       <item row="1" column="0">
         <widget class="QLabel" name="label_17">
          <property name="text">
           <string>User Interface &amp;layout (needs restart):</string>
@@ -38,7 +65,7 @@
          </property>
         </widget>
        </item>
-       <item row="0" column="1">
+       <item row="1" column="1">
         <widget class="QComboBox" name="opt_gui_layout">
          <property name="maximumSize">
           <size>
@@ -54,34 +81,7 @@
          </property>
         </widget>
        </item>
-       <item row="1" column="0">
+       <item row="3" column="1">
-        <widget class="QLabel" name="label_7">
-         <property name="text">
-          <string>Choose &amp;language (requires restart):</string>
-         </property>
-         <property name="buddy">
-          <cstring>opt_language</cstring>
-         </property>
-        </widget>
-       </item>
-       <item row="1" column="1">
-        <widget class="QComboBox" name="opt_language">
-         <property name="sizeAdjustPolicy">
-          <enum>QComboBox::AdjustToMinimumContentsLengthWithIcon</enum>
-         </property>
-         <property name="minimumContentsLength">
-          <number>20</number>
-         </property>
-        </widget>
-       </item>
-       <item row="2" column="0">
-        <widget class="QCheckBox" name="opt_systray_icon">
-         <property name="text">
-          <string>Enable system &amp;tray icon (needs restart)</string>
-         </property>
-        </widget>
-       </item>
-       <item row="2" column="1">
         <widget class="QCheckBox" name="opt_disable_animations">
          <property name="toolTip">
           <string>Disable all animations. Useful if you have a slow/old computer.</string>
@@ -91,21 +91,21 @@
          </property>
         </widget>
        </item>
-       <item row="3" column="0">
+       <item row="4" column="0">
         <widget class="QCheckBox" name="opt_disable_tray_notification">
          <property name="text">
           <string>Disable &amp;notifications in system tray</string>
          </property>
         </widget>
        </item>
-       <item row="3" column="1">
+       <item row="4" column="1">
         <widget class="QCheckBox" name="opt_show_splash_screen">
          <property name="text">
           <string>Show &amp;splash screen at startup</string>
          </property>
         </widget>
        </item>
-       <item row="5" column="0" colspan="2">
+       <item row="6" column="0" colspan="2">
         <widget class="QGroupBox" name="groupBox_2">
          <property name="title">
           <string>&amp;Toolbar</string>
@@ -140,7 +140,20 @@
          </layout>
         </widget>
        </item>
-       <item row="4" column="0">
+       <item row="7" column="0">
+        <spacer name="verticalSpacer_3">
+         <property name="orientation">
+          <enum>Qt::Vertical</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>20</width>
+           <height>40</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+       <item row="5" column="0">
         <layout class="QHBoxLayout" name="horizontalLayout">
          <item>
           <widget class="QLabel" name="label_2">
@@ -161,25 +174,25 @@
          </item>
         </layout>
        </item>
-       <item row="4" column="1">
+       <item row="5" column="1">
         <widget class="QPushButton" name="change_font_button">
          <property name="text">
           <string>Change &amp;font (needs restart)</string>
          </property>
         </widget>
        </item>
-       <item row="6" column="0">
+       <item row="0" column="0">
-        <spacer name="verticalSpacer_3">
+        <widget class="QLabel" name="label_4">
-         <property name="orientation">
+         <property name="text">
-          <enum>Qt::Vertical</enum>
+          <string>User interface &amp;style (needs restart):</string>
          </property>
-         <property name="sizeHint" stdset="0">
+         <property name="buddy">
-          <size>
+          <cstring>opt_widget_style</cstring>
-           <width>20</width>
-           <height>40</height>
-          </size>
          </property>
-        </spacer>
+        </widget>
+       </item>
+       <item row="0" column="1">
+        <widget class="QComboBox" name="opt_widget_style"/>
        </item>
       </layout>
      </widget>