Group group = quadMap.getActiveGroup();
if (group.getFields().contains(position)) {
UnmarkField unmarkField = new UnmarkField(group, position);
unmarkField.execute();
} else {
MarkField markField = new MarkField(group, position);
markField.execute();
}
} else {
Messages.getMessages().info("QuadIsoLayTerrainView", "QMapWarn",
"When executing mark-only-field: QuadMap has "
+ "no game-data");