#define IS_VIK_LAYER(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), VIK_LAYER_TYPE))
#define IS_VIK_LAYER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), VIK_LAYER_TYPE))
#define IS_VIK_LAYER(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), VIK_LAYER_TYPE))
#define IS_VIK_LAYER_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), VIK_LAYER_TYPE))