Err, doesn't GTK offer a widget that can reflow automatically? Manually inserting newlines is a mess, especially w.r.t. translations?
Well, there's `geany_wrap_label_new()` but it's not exported to plugins and I'm not sure if it behaves 100% correctly - when you open Tools->Plugin manager, it's used for the top label but emits lots of errors to the console:
``` (geany:3677166): Gtk-WARNING **: 11:16:48.477: Negative content width -17 (allocation 1, extents 9x9) while allocating gadget (node entry, owner GtkEntry)
(geany:3677166): Gtk-WARNING **: 11:16:48.477: Negative content height -1 (allocation 1, extents 1x1) while allocating gadget (node entry, owner GtkEntry)
(geany:3677166): Gtk-WARNING **: 11:16:48.477: Negative content width -1 (allocation 1, extents 1x1) while allocating gadget (node scrolledwindow, owner GtkScrolledWindow)
(geany:3677166): Gtk-WARNING **: 11:16:48.477: Negative content height -1 (allocation 1, extents 1x1) while allocating gadget (node scrolledwindow, owner GtkScrolledWindow)
(geany:3677166): Gtk-CRITICAL **: 11:16:48.477: gtk_box_gadget_distribute: assertion 'size >= 0' failed in GtkScrollbar
(geany:3677166): Gtk-CRITICAL **: 11:16:48.477: gtk_widget_get_preferred_width_for_height: assertion 'height >= 0' failed
(geany:3677166): Gtk-WARNING **: 11:16:48.477: gtk_widget_size_allocate(): attempt to allocate widget with width 11 and height -23
(geany:3677166): Gtk-CRITICAL **: 11:16:48.477: gtk_box_gadget_distribute: assertion 'size >= 0' failed in GtkScrollbar ```
Apart from that I don't know anything (but I don't know GTK :-)