Looking at the code ui_lookup_widget seems to only look for siblings, not search down the widget tree.
It searches for a top-level widget, because Glade calls e.g. `g_object_set_data` on top-level widgets.
The lookup does seem to work, the following prints 1: ``` g_warning("%d", GTK_IS_TREE_VIEW(ui_lookup_widget(main_widgets.window, "treeview2"))); ``` The weird thing is that `gtk_widget_grab_widget` with that lookup doesn't work. It does work if we focus the entry, which might be more useful anyway: ``` gtk_widget_grab_focus(ui_lookup_widget(main_widgets.window, "entry_tagfilter")); ``` BTW I tested the pull and the code there seems to work.