Hi, The code fragment sent before was compiling fine under earlier versions i.e. gtk+ 1.2.5. When I checked the gtknotebook.h file there is no struct type decleration for _GTKNotebookPage. It is defined explicitly in gtknotebook.c file hence in one of the object files of gtk. That is why in the help files for GTK says "The GtkNotebookPage is an opaque implementation detail of GtkNotebook." and I don't know how to solve this problem of dereferencing. I think it is kind of versione problem but not sure. Please some advice: >You're probably passing in a bad pointer. Hi, Any idea how to solve this dereferencing problem? Thank you in advanced. ========= ERROR ======== GtkNotebookPagegtsrc.c: In function `set_notebook_tab': gtsrc.c:144: error: dereferencing pointer to incomplete type ====CODE ======== /* This is an internally used function to set notebook tab widgets. */ void set_notebook_tab (GtkWidget *notebook, gint page_num, GtkWidget *widget) { GtkNotebookPage *page; GtkWidget *notebook_page; page = (GtkNotebookPage*) g_list_nth (GTK_NOTEBOOK (notebook)->children, page_num)->data; notebook_page = page->child; // LINE 144 gtk_widget_ref (notebook_page); gtk_notebook_remove_page (GTK_NOTEBOOK (notebook), page_num); gtk_notebook_insert_page (GTK_NOTEBOOK (notebook), notebook_page, widget, page_num); gtk_widget_unref (notebook_page); } _______________________________________________ gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list