gtk_toolbar_prepend_item has been deprecated since version 2.4 and should not be used in newly-written code. Use gtkToolbarInsert instead.
gtkToolbarPrependItem(object, text, tooltip.text, tooltip.private.text, icon, callback, user.data)objectGtkToolbar.texttooltip.texttooltip.private.textGtkTipsQuery.iconGtkWidget that should be used as the button's icon.callbackuser.datacallback must be a pointer to a function taking a GtkWidget and a gpointer as
arguments. Use gCallback() to cast the function to GCallback.