gtk_source_undo_manager_begin_not_undoable_action / gtk_source_undo_manager_end_not_undoable_action not working

Question

I'm trying to write my own text editor in C using gtk+-2.0 & gtksourceview-2.0. I've been using the gedit source when I get stuck, but they apparently don't use this functionality and I can't find an example of its use online. When I open a text file and place its contents into the text buffer this is registered as an undoable action. I would like this process to be not undoable, so I have placed:

gtk_source_undo_manager_begin_not_undoable_action(um);

at the beginning of my open_activated function (provided below), and:

gtk_source_undo_manager_end_not_undoable_action(um);

at the end of this same function. According to the help provided in devHelp it says that everything in between these two lines should not be undoable, but it is. What am I missing? Is there a better way to accomplish this same functionality?

GtkSourceUndoManager *um; (defined globally)

void open_activated(GtkWidget *widget, GtkWindow *parent)
{
  GtkSourceLanguage *lang;
  GtkSourceLanguageManager *lm;
  GtkWidget *dialog;
  int pages = 0;
  GtkWidget *tablabel;

  gtk_source_undo_manager_begin_not_undoable_action(um);

  /* create new tab */
  tablabel = gtk_label_new("New File");
  pages = gtk_notebook_get_n_pages(GTK_NOTEBOOK(notebook));
  gtk_container_add(GTK_CONTAINER(scrollwin[pages]),txtinput[pages]);
  gtk_widget_show_all (scrollwin[pages]);
  gtk_notebook_append_page(GTK_NOTEBOOK(notebook),scrollwin[pages],tablabel);
  //gtk_source_view_set_show_line_numbers (GTK_SOURCE_VIEW (txtinput[pages]), TRUE);
  gtk_notebook_set_current_page (GTK_NOTEBOOK(notebook), pages);

  //gtk_text_buffer_set_modified (gtk_text_view_get_buffer((GTK_TEXT_VIEW(txtinput[pages]))), TRUE);

  dialog = gtk_file_chooser_dialog_new("Open File", parent, GTK_FILE_CHOOSER_ACTION_OPEN,GTK_STOCK_CANCEL,GTK_RESPONSE_CANCEL,GTK_STOCK_OPEN,GTK_RESPONSE_ACCEPT,NULL);
  GtkTextBuffer *buffer;
  //buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(txtinput[gtk_notebook_get_current_page(GTK_NOTEBOOK(notebook))]));
  buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(txtinput[pages]));


  if(gtk_dialog_run(GTK_DIALOG(dialog))== GTK_RESPONSE_ACCEPT)
  {
    char *path,*string;
    const gchar *filename;
    char temp[40];
    gsize length = -1;
    path = gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(dialog));
    paths[pages] = path;
    filename = filenameFromPath(path);
    //printf("%s\n",out);
    strcpy(temp,filename);
    tablabel = gtk_label_new(temp);
    g_file_get_contents(path,&string,&length,NULL);     
    gtk_text_buffer_set_text(buffer,string,-1);

    /* syntax highlighting */
    lm = gtk_source_language_manager_new();
    lang = gtk_source_language_manager_guess_language (lm, path, NULL);
    gtk_source_buffer_set_language (GTK_SOURCE_BUFFER(buffer), lang);

    /* change tab label */
    gtk_notebook_set_tab_label (GTK_NOTEBOOK(notebook), scrollwin[pages], tablabel);

    /* set some sourceview options */
    gtk_source_view_set_show_line_numbers (GTK_SOURCE_VIEW (txtinput[pages]), TRUE);
    gtk_source_view_set_tab_width (GTK_SOURCE_VIEW (txtinput[pages]), 2);

    /* Set the editor's font. */
    PangoFontDescription *font_desc = pango_font_description_new();
    pango_font_description_set_family (font_desc, "monospace");
    gtk_widget_modify_font (txtinput[pages], font_desc);

    g_free(path);
    g_free(string);

  }

  gtk_widget_destroy(dialog);
  gtk_text_buffer_set_modified (gtk_text_view_get_buffer((GTK_TEXT_VIEW(txtinput[pages]))), FALSE);
  changeLabelColor("black");

  gtk_source_undo_manager_end_not_undoable_action(um);

}

---

Unfortunately there isn't any gtk_source_undo_manager_new () or gtk_source_undo_manager_get_default () like there is for the language manager. The documentation for the GtkSourceUndoManager is:

Description

The GtkSourceUndoManager interface can be implemented to provide custom undo management to a GtkSourceBuffer. Use gtk_source_buffer_set_undo_manager to install a custom undo manager for a particular source buffer.

Use gtk_source_undo_manager_can_undo_changed and gtk_source_undo_manager_can_redo_changed when respectively the undo state or redo state of the undo stack has changed.

Details

GtkSourceUndoManager

typedef struct _GtkSourceUndoManager GtkSourceUndoManager;

GtkSourceUndoManagerIface

typedef struct {
GTypeInterface parent;

/* Interface functions */
gboolean (*can_undo)                  (GtkSourceUndoManager *manager);
gboolean (*can_redo)                  (GtkSourceUndoManager *manager);

void     (*undo)                      (GtkSourceUndoManager *manager);
void     (*redo)                      (GtkSourceUndoManager *manager);

void     (*begin_not_undoable_action) (GtkSourceUndoManager *manager);
void     (*end_not_undoable_action)   (GtkSourceUndoManager *manager);

/* Signals */
void     (*can_undo_changed)          (GtkSourceUndoManager *manager);
void     (*can_redo_changed)          (GtkSourceUndoManager *manager);
} GtkSourceUndoManagerIface;

Answer 1

If you're not implementing a custom undo manager, then just use gtk_source_buffer_begin_not_undoable_action() instead.