Edit book: Add a shortcut Ctrl+M to merge selected files. Fixes #2053144 [ebook-edit: Keyboard shortcut for merging files](https://bugs.launchpad.net/calibre/+bug/2053144)

src/calibre/gui2/tweak_book/boss.py

@@ -1911,6 +1911,9 @@ class Boss(QObject):
         from calibre.gui2.tweak_book.editor.snippets import UserSnippets
         UserSnippets(self.gui).exec()
 
+    def merge_files(self):
+        self.gui.file_list.merge_files()
+
     # Shutdown {{{
 
     def quit(self):

src/calibre/gui2/tweak_book/file_list.py

@@ -766,6 +766,22 @@ class FileList(QTreeWidget, OpenWithHandler):
                     return (category, i)
         return (None, -1)
 
+    def merge_files(self):
+        sel = self.selectedItems()
+        selected_map = defaultdict(list)
+        for item in sel:
+            selected_map[str(item.data(0, CATEGORY_ROLE) or '')].append(str(item.data(0, NAME_ROLE) or ''))
+
+        for items in selected_map.values():
+            items.sort(key=self.index_of_name)
+        if len(selected_map['text']) > 1:
+            self.start_merge('text', selected_map['text'])
+        elif len(selected_map['styles']) > 1:
+            self.start_merge('styles', selected_map['styles'])
+        else:
+            error_dialog(self, _('Cannot merge'), _(
+                'No files selected. Select two or more HTML files or two or more CSS files in the Files browser before trying to merge'), show=True)
+
     def start_merge(self, category, names):
         d = MergeDialog(names, self)
         if d.exec() == QDialog.DialogCode.Accepted and d.ans:
@@ -1264,6 +1280,9 @@ class FileListWidget(QWidget):
     def restore_temp_names(self):
         self.file_list.restore_temp_names()
 
+    def merge_files(self):
+        self.file_list.merge_files()
+
     @property
     def searchable_names(self):
         return self.file_list.searchable_names

src/calibre/gui2/tweak_book/ui.py

@@ -559,6 +559,9 @@ class Main(MainWindow):
         self.action_manage_snippets = treg(
             'snippets.png', _('Manage &Snippets'), self.boss.manage_snippets, 'manage-snippets', (), _(
                 'Manage user created Snippets'))
+        self.action_merge_files = treg(
+            'merge.png', _('&Merge files'), self.boss.merge_files, 'merge-files', 'Ctrl+M', _(
+                'Merge two or more selected files'))
 
         self.plugin_menu_actions = []