Use the default row height for the book list, rather than resizing to contents, as the Fusion style has a nice default row height

Also allow both increasing and decreasing of the row height

src/calibre/gui2/__init__.py

@@ -111,7 +111,7 @@ defs['bd_show_cover'] = True
 defs['bd_overlay_cover_size'] = False
 defs['tags_browser_category_icons'] = {}
 defs['cover_browser_reflections'] = True
-defs['extra_row_spacing'] = 0
+defs['book_list_extra_row_spacing'] = 0
 defs['refresh_book_list_on_bulk_edit'] = True
 defs['cover_grid_width'] = 0
 defs['cover_grid_height'] = 0

src/calibre/gui2/library/views.py

@@ -163,6 +163,7 @@ class BooksView(QTableView):  # {{{
 
     def __init__(self, parent, modelcls=BooksModel, use_edit_metadata_dialog=True):
         QTableView.__init__(self, parent)
+        self.default_row_height = self.verticalHeader().defaultSectionSize()
         self.gui = parent
         self.setProperty('highlight_current_item', 150)
         self.row_sizing_done = False
@@ -658,9 +659,8 @@ class BooksView(QTableView):  # {{{
     def do_row_sizing(self):
         # Resize all rows to have the correct height
         if not self.row_sizing_done and self.model().rowCount(QModelIndex()) > 0:
-            self.resizeRowToContents(0)
-            self.verticalHeader().setDefaultSectionSize(self.rowHeight(0) +
-                                            gprefs['extra_row_spacing'])
+            vh = self.verticalHeader()
+            vh.setDefaultSectionSize(max(vh.minimumSectionSize(), self.default_row_height + gprefs['book_list_extra_row_spacing']))
             self._model.set_row_height(self.rowHeight(0))
             self.row_sizing_done = True
 

src/calibre/gui2/preferences/look_feel.py

@@ -157,6 +157,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         r('emblem_size', gprefs)
         r('emblem_position', gprefs, choices=[
             (_('Left'), 'left'), (_('Top'), 'top'), (_('Right'), 'right'), (_('Bottom'), 'bottom')])
+        r('book_list_extra_row_spacing', gprefs)
 
         def get_esc_lang(l):
             if l == 'en':

src/calibre/gui2/preferences/look_feel.ui

@@ -207,18 +207,18 @@
           <string>Extra &amp;spacing to add between rows in the book list:</string>
          </property>
          <property name="buddy">
-          <cstring>opt_extra_row_spacing</cstring>
+          <cstring>opt_book_list_extra_row_spacing</cstring>
          </property>
         </widget>
        </item>
        <item row="8" column="1">
-        <widget class="QSpinBox" name="opt_extra_row_spacing">
-         <property name="specialValueText">
-          <string>None</string>
-         </property>
+        <widget class="QSpinBox" name="opt_book_list_extra_row_spacing">
          <property name="suffix">
           <string> px</string>
          </property>
+         <property name="minimum">
+          <number>-5</number>
+         </property>
         </widget>
        </item>
       </layout>