Viewer: Allow customizing what actions appear on the toolbar (Preferences->Miscellaneous->Customize toolbar). Fixes #1852017 [Rearrange the optional toolbar icons](https://bugs.launchpad.net/calibre/+bug/1852017)

src/calibre/gui2/viewer/toolbars.py

@@ -108,6 +108,7 @@ class ActionsToolBar(ToolBar):
         page = web_view.page()
         web_view.paged_mode_changed.connect(self.update_mode_action)
         web_view.standalone_misc_settings_changed.connect(self.update_visibility)
+        web_view.customize_toolbar.connect(self.customize, type=Qt.QueuedConnection)
 
         self.back_action = page.action(QWebEnginePage.Back)
         self.back_action.setIcon(aa.back.icon)
@@ -199,6 +200,11 @@ class ActionsToolBar(ToolBar):
     def update_visibility(self):
         self.setVisible(bool(get_session_pref('show_actions_toolbar', default=False)))
 
+    def customize(self):
+        d = ConfigureToolBar(parent=self.parent())
+        if d.exec_() == d.Accepted:
+            self.add_actions()
+
 
 class ActionsList(QListWidget):
 
@@ -323,6 +329,7 @@ class ConfigureToolBar(Dialog):
             vprefs.__delitem__('actions-toolbar-actions')
         else:
             vprefs.set('actions-toolbar-actions', ans)
+        return Dialog.accept(self)
 
 
 if __name__ == '__main__':

src/calibre/gui2/viewer/web_view.py

@@ -258,6 +258,7 @@ class ViewerBridge(Bridge):
     print_book = from_js()
     clear_history = from_js()
     reset_interface = from_js()
+    customize_toolbar = from_js()
 
     create_view = to_js()
     start_book_load = to_js()
@@ -414,6 +415,7 @@ class WebView(RestartingWebEngineView):
     show_error = pyqtSignal(object, object, object)
     print_book = pyqtSignal()
     reset_interface = pyqtSignal()
+    customize_toolbar = pyqtSignal()
     shortcuts_changed = pyqtSignal(object)
     paged_mode_changed = pyqtSignal()
     standalone_misc_settings_changed = pyqtSignal(object)
@@ -452,6 +454,7 @@ class WebView(RestartingWebEngineView):
         self.bridge.print_book.connect(self.print_book)
         self.bridge.clear_history.connect(self.clear_history)
         self.bridge.reset_interface.connect(self.reset_interface)
+        self.bridge.customize_toolbar.connect(self.customize_toolbar)
         self.bridge.export_shortcut_map.connect(self.set_shortcut_map)
         self.shortcut_map = {}
         self.bridge.report_cfi.connect(self.call_callback)

src/pyj/read_book/prefs/misc.pyj

@@ -7,9 +7,10 @@ from gettext import gettext as _
 
 from book_list.globals import get_session_data
 from dom import unique_id
-from session import defaults
+from read_book.globals import ui_operations
 from read_book.prefs.utils import create_button_box
-
+from session import defaults
+from widgets import create_button
 
 CONTAINER = unique_id('standalone-misc-settings')
 DEFAULTS = {
@@ -46,6 +47,9 @@ def create_misc_panel(container, apply_func, cancel_func):
 
     container.append(cb('remember_window_geometry', _('Remember last used window size and position')))
     container.append(cb('show_actions_toolbar', _('Show a toolbar with the most useful actions')))
+    container.lastChild.append(E.span('\xa0'))
+    container.lastChild.append(
+        create_button(_('Customize toolbar'), action=ui_operations.customize_toolbar))
     container.append(cb('remember_last_read', _('Remember current page when quitting')))
     container.append(cb('save_annotations_in_ebook', _('Keep a copy of annotations/bookmarks in the e-book file, for easy sharing')))
     container.append(cb('singleinstance', _('Allow only a single instance of the viewer (needs restart)')))

src/pyj/viewer-main.pyj

@@ -377,6 +377,8 @@ if window is window.top:
         to_python.print_book()
     ui_operations.clear_history = def():
         to_python.clear_history()
+    ui_operations.customize_toolbar = def():
+        to_python.customize_toolbar()
 
     document.body.appendChild(E.div(id='view'))
     window.onerror = onerror