gtk_button_new_from_stock()     -> gtk_button_new_from_icon_name()
gtk_widget_render_icon_pixbuf() -> gtk_icon_theme_load_icon()
gtk_widget_set_margin_left()    -> gtk_widget_set_margin_start()

Stock images with icon names
GTK_STOCK_ADD     -> "list-add"
GTK_STOCK_REMOVE  -> "list-remove"
GTK_STOCK_OPEN    -> "document-open"
GTK_STOCK_GO_DOWN -> "go-down"
GTK_STOCK_DIALOG_WARNING -> "dialog-warning"
GTK_STOCK_INFO    -> "dialog-information"
GTK_STOCK_SAVE    -> "document-save"
GTK_STOCK_REFRESH -> "view-refresh"