add menu entries and shortcuts for zoom functions in the editor (bug #41516) * file-editor.cc (zoom_in): slot for zoom-in action, triggering signal for tab; (zoom_out): slot for zoom-out action, triggering signal for tab; (zoom_normal): slot for zoom-to-normal action, triggering signal for tab; (construct): new View-menu with zoom-in, zoom-out and zoom-normal entries; (add_file_editor_tab): connect zoom-signal to newly created tabs; (set_shortcuts): set shortcuts for new zoom actions; (check_actions): disable zoom action when no editor tab is open * file-editor.h: zoom-in, zoom-out and zoom-normal actions, related slots and related signals to the actual tab * file-editor-tab.cc (zoom_in): new slot for signal from file_editor; (zoom_out): new slot for signal from file_editor; (zoom_normal): new slot for signal from file_editor * file-editor-tab.h: new slots zoom_in, zoom_out, zoom_normal * octave-qscintilla.cc (constructor): disable the shortcuts qscintilla uses for the zoom-actions in order to be able to use own functions

--- a/libgui/src/m-editor/file-editor.h
+++ b/libgui/src/m-editor/file-editor.h
@@ -104,6 +104,11 @@
   void fetab_do_breakpoint_marker (bool insert, const QWidget* ID,
                                    int line = -1);
   void fetab_set_focus (const QWidget* ID);
+
+  void fetab_zoom_in (const QWidget* ID);
+  void fetab_zoom_out (const QWidget* ID);
+  void fetab_zoom_normal (const QWidget* ID);
+
   void request_settings_dialog (const QString&);
   void execute_command_in_terminal_signal (const QString&);
   void file_loaded_signal ();
@@ -196,6 +201,10 @@
   void request_styles_preferences (bool);
   void restore_create_file_setting ();
 
+  void zoom_in (bool);
+  void zoom_out (bool);
+  void zoom_normal (bool);
+
 private:
 
   bool is_editor_console_tabbed ();
@@ -228,6 +237,10 @@
   QAction *_context_help_action;
   QAction *_context_doc_action;
 
+  QAction *_zoom_in_action;
+  QAction *_zoom_out_action;
+  QAction *_zoom_normal_action;
+
   QAction *_find_action;
   QAction *_goto_line_action;
   QAction *_completion_action;