Fix filename for save as dialog

src/dialogs.cc

@@ -5,12 +5,15 @@
 
 std::string open_dialog(const std::string &title,
                         const std::vector<std::pair<std::string, Gtk::ResponseType>> &buttons,
-                        Gtk::FileChooserAction gtk_options) {
+                        Gtk::FileChooserAction gtk_options,
+                        const std::string &file_name = "") {
   Gtk::FileChooserDialog dialog(title, gtk_options);
   if(Singleton::directories()->current_path!="")
     gtk_file_chooser_set_current_folder((GtkFileChooser*)dialog.gobj(), Singleton::directories()->current_path.string().c_str());
   else
     gtk_file_chooser_set_current_folder((GtkFileChooser*)dialog.gobj(), boost::filesystem::current_path().string().c_str());
+  if (!file_name.empty())
+    gtk_file_chooser_set_filename((GtkFileChooser*)dialog.gobj(), file_name.c_str());
   dialog.set_position(Gtk::WindowPosition::WIN_POS_CENTER_ALWAYS);
   dialog.set_transient_for(*Singleton::window()); 
   for (auto &button : buttons) 
@@ -45,6 +48,7 @@ std::string Dialog::select_file() {
 std::string Dialog::save_file() {
   return open_dialog("Please choose a file",
             {std::make_pair("Cancel", Gtk::RESPONSE_CANCEL),std::make_pair("Save", Gtk::RESPONSE_OK)},
-            Gtk::FILE_CHOOSER_ACTION_SAVE);
+                     Gtk::FILE_CHOOSER_ACTION_SAVE,
+                     Singleton::window()->notebook.get_current_view()->file_path.string());
 }