Problem in insert toolbar

[brcontainer]

I still do not understand GTK, but apparently this line is not working and is sending a problem: https://github.com/tgdn/browser/blob/master/tabview.c#L91

gtk_toolbar_insert(GTK_TOOLBAR(toolbar), GTK_TOOL_ITEM(entries_paned), 3);

No create element.

[tgdn]

What is the error that you get?
The toolbar is created on this line

GtkWidget *toolbar = gtk_toolbar_new();