@elextr @codebrainz
This code applies rotation accordingly and works for Geany-own tabs as well tabs inserted by plugins.
``` GtkNotebook *sidebarNotebook = GTK_NOTEBOOK(ui_lookup_widget(geany->main_widgets->window, "notebook3")); for (GList *iterator = gtk_container_get_children(sidebarNotebook); iterator; iterator = iterator->next) { GtkLabel *sidebarLabel = gtk_notebook_get_tab_label(sidebarNotebook, iterator->data); gtk_label_set_angle(sidebarLabel, 90); } ``` You can do what you want with that piece, public domain.