void shumate_marker_layer_unselect_marker ( ShumateMarkerLayer* self, ShumateMarker* marker )
Unselects a marker in this layer.
This works even if
GTK_SELECTION_BROWSE. Browse mode only prevents user interaction, not the
program, from unselecting a marker.
ShumateMarkerthat is a child of
The data is owned by the caller of the method.