make copying figures to clipboard work (bug #44866) * Figure.cc (Figure::copy_figure_callback): Just print the figure to a file here, then call octave_link::copy_image_to_clipboard. (delete_file): Delete unused static function. * main-window.h, main-window.cc (main_window::copy_image_to_clipboard): New function. (main_window::construct_octave_qt_link): Connect octave_qt_link::copy_image_to_clipboard_signal signal to main_window::copy_image_to_clipboard slot. * octave-qt-link.h, octave-qt-link.cc (octave_qt_link::do_copy_image_to_clipboard): New function. (octave_qt_link::copy_image_to_clipboard_signal): New signal. * octave-link.h (octave_link::do_copy_image_to_clipboard): New pure virtual function. (octave_link::copy_image_to_clipboard): New static funtion.

--- a/libgui/src/octave-qt-link.h
+++ b/libgui/src/octave-qt-link.h
@@ -64,6 +64,8 @@
   bool do_confirm_shutdown (void);
   bool do_exit (int status);
 
+  bool do_copy_image_to_clipboard (const std::string& file);
+
   bool do_edit_file (const std::string& file);
   bool do_prompt_new_edit_file (const std::string& file);
 
@@ -157,6 +159,8 @@
 
   void execute_interpreter_signal (void);
 
+  void copy_image_to_clipboard_signal (const QString& file, bool remove_file);
+
   void edit_file_signal (const QString& file);
 
   void change_directory_signal (const QString& dir);