Fix #1857923 [[Enhancement] Remeber last paths in automatic adding](https://bugs.launchpad.net/calibre/+bug/1857923)

src/calibre/gui2/convert/debug.ui

@@ -63,9 +63,6 @@
    </item>
    <item row="1" column="0">
     <widget class="QLineEdit" name="opt_debug_pipeline">
-     <property name="readOnly">
-      <bool>true</bool>
-     </property>
      <property name="clearButtonEnabled">
       <bool>true</bool>
      </property>

src/calibre/gui2/preferences/__init__.py

@@ -15,6 +15,7 @@
 from calibre.customize.ui import preferences_plugins
 from calibre.utils.config import ConfigProxy
 from calibre.gui2.complete2 import EditWithComplete
+from calibre.gui2.widgets import HistoryLineEdit
 from polyglot.builtins import unicode_type, string_or_bytes
 
 
@@ -109,9 +110,11 @@ def __init__(self, name, config_obj, widget, gui_name=None,
         elif isinstance(self.gui_obj, QAbstractSpinBox):
             self.datatype = 'number'
             self.gui_obj.valueChanged.connect(self.changed)
-        elif isinstance(self.gui_obj, QLineEdit):
+        elif isinstance(self.gui_obj, (QLineEdit, HistoryLineEdit)):
             self.datatype = 'string'
             self.gui_obj.textChanged.connect(self.changed)
+            if isinstance(self.gui_obj, HistoryLineEdit):
+                self.gui_obj.initialize('preferences_setting_' + self.name)
         elif isinstance(self.gui_obj, QComboBox):
             self.datatype = 'choice'
             self.gui_obj.editTextChanged.connect(self.changed)

src/calibre/gui2/preferences/adding.py

@@ -93,6 +93,7 @@ def choose_aa_path(self):
                 _('Choose a folder'))
         if path:
             self.opt_auto_add_path.setText(path)
+            self.opt_auto_add_path.save_history()
 
     def initialize(self):
         ConfigWidgetBase.initialize(self)

src/calibre/gui2/preferences/adding.ui

@@ -17,7 +17,7 @@
    <item row="0" column="0">
     <widget class="QTabWidget" name="tabWidget">
      <property name="currentIndex">
-      <number>0</number>
+      <number>2</number>
      </property>
      <widget class="QWidget" name="tab">
       <attribute name="title">
@@ -313,10 +313,13 @@ that have been explicitly ignored below.</string>
        <item row="1" column="0" colspan="2">
         <layout class="QHBoxLayout" name="horizontalLayout_2">
          <item>
-          <widget class="QLineEdit" name="opt_auto_add_path">
+          <widget class="HistoryLineEdit" name="opt_auto_add_path">
            <property name="placeholderText">
             <string>Folder to automatically add files from</string>
            </property>
+           <property name="clearButtonEnabled">
+            <bool>true</bool>
+           </property>
           </widget>
          </item>
          <item>
@@ -436,6 +439,13 @@ that have been explicitly ignored below.</string>
    </item>
   </layout>
  </widget>
+ <customwidgets>
+  <customwidget>
+   <class>HistoryLineEdit</class>
+   <extends>QLineEdit</extends>
+   <header>calibre/gui2/widgets.h</header>
+  </customwidget>
+ </customwidgets>
  <resources>
   <include location="../../../../resources/images.qrc"/>
  </resources>

src/calibre/gui2/widgets.py

@@ -669,6 +669,7 @@ def __init__(self, *args):
         self.setInsertPolicy(self.NoInsert)
         self.setMaxCount(10)
         self.setClearButtonEnabled = self.lineEdit().setClearButtonEnabled
+        self.textChanged = self.editTextChanged
 
     def setPlaceholderText(self, txt):
         return self.lineEdit().setPlaceholderText(txt)