Remove the bright yellow lines indicating hidden sections as they dont seem to communicate that very well to most users. We will just have to rely on the buttons in the bottom right corner to indicate sections are hidden.

resources/default_tweaks.py

@@ -442,12 +442,6 @@ metadata_edit_custom_column_order = []
 # calibre.
 public_smtp_relay_delay = 301
 
-#: Remove the bright yellow lines at the edges of the book list
-# Control whether the bright yellow lines at the edges of book list are drawn
-# when a section of the user interface is hidden. Changes will take effect
-# after a restart of calibre.
-draw_hidden_section_indicators = True
-
 #: The maximum width and height for covers saved in the calibre library
 # All covers in the calibre library will be resized, preserving aspect ratio,
 # to fit within this size. This is to prevent slowdowns caused by extremely

src/calibre/gui2/init.py

@@ -238,10 +238,11 @@ class LayoutMixin(object): # {{{
         # }}}
 
         self.status_bar = StatusBar(self)
+        stylename = unicode(self.style().objectName())
         for x in button_order:
             button = getattr(self, x+'_splitter').button
             button.setIconSize(QSize(24, 24))
-            if isosx:
+            if isosx and stylename != u'Calibre':
                 button.setStyleSheet('''
                         QToolButton { background: none; border:none; padding: 0px; }
                         QToolButton:checked { background: rgba(0, 0, 0, 25%); }

src/calibre/gui2/widgets.py

@@ -21,7 +21,7 @@ from calibre.gui2 import (NONE, error_dialog, pixmap_to_data, gprefs,
 from calibre.gui2.filename_pattern_ui import Ui_Form
 from calibre import fit_image
 from calibre.ebooks import BOOK_EXTENSIONS
-from calibre.utils.config import prefs, XMLConfig, tweaks
+from calibre.utils.config import prefs, XMLConfig
 from calibre.gui2.progress_indicator import ProgressIndicator as _ProgressIndicator
 from calibre.gui2.dnd import (dnd_has_image, dnd_get_image, dnd_get_files,
     IMAGE_EXTENSIONS, dnd_has_extension, DownloadDialog)
@@ -1000,13 +1000,6 @@ class SplitterHandle(QSplitterHandle):
         if oh != self.highlight:
             self.update()
 
-    def paintEvent(self, ev):
-        QSplitterHandle.paintEvent(self, ev)
-        if self.highlight and tweaks['draw_hidden_section_indicators']:
-            painter = QPainter(self)
-            painter.setClipRect(ev.rect())
-            painter.fillRect(self.rect(), Qt.yellow)
-
     def mouseDoubleClickEvent(self, ev):
         self.double_clicked.emit(self)