Renders an icon of given size. The base of the icon is set by the last call
to one of: gtk_source_mark_attributes_set_pixbuf(),
gtk_source_mark_attributes_set_gicon(),
gtk_source_mark_attributes_set_icon_name() or
gtk_source_mark_attributes_set_stock_id(). size cannot be lower than 1.
Renders an icon of given size. The base of the icon is set by the last call to one of: gtk_source_mark_attributes_set_pixbuf(), gtk_source_mark_attributes_set_gicon(), gtk_source_mark_attributes_set_icon_name() or gtk_source_mark_attributes_set_stock_id(). size cannot be lower than 1.