give your toolbar button a label.
a string that appears when the user holds the mouse over this item.
use with GtkTipsQuery.
a GtkWidget that should be used as the button's icon.
the function to be executed when the button is pressed.
a pointer to any data you wish to be passed to the callback.
the new toolbar item as a GtkWidget.
Warning gtk_toolbar_prepend_item has been deprecated since version 2.4 and should not be used in newly-written code. Use gtk_toolbar_insert() instead. Adds a new button to the beginning (top or left edges) of the given toolbar. callback must be a pointer to a function taking a GtkWidget and a gpointer as arguments. Use G_CALLBACK() to cast the function to GCallback.