diff --git a/src/eva2/gui/FunctionArea.java b/src/eva2/gui/FunctionArea.java
index db26bd87..0d086cd9 100644
--- a/src/eva2/gui/FunctionArea.java
+++ b/src/eva2/gui/FunctionArea.java
@@ -131,11 +131,43 @@ public class FunctionArea extends DArea implements Serializable {
 	  * @param graphID
 	  */
 	 public void drawCircle(String label, double[] position, int graphID) {
+		 drawIcon(new Chart2DDPointIconCircle(), label, position, graphID);
+	 }
+	 
+	 /**
+	  * Plot an icon to the function area which is annotated with a char and
+	  * a double value. The color corresponds to the color of the graph with given ID
+	  * Icon types are 0: circle, 1: cross, otherwise: point.
+	  * 
+	  * @param label
+	  * @param position
+	  * @param graphID
+	  */
+	 public void drawIcon(int iconType, String label, double[] position, int graphID) {
+		 DPointIcon theIcon;
+		 switch (iconType) {
+		 case 0: theIcon = new Chart2DDPointIconCircle(); break;
+		 case 1: theIcon = new Chart2DDPointIconCross(); break;
+		 default:
+		 case 2: theIcon = new Chart2DDPointIconPoint(); break;
+		 }
+		 drawIcon(theIcon, label, position, graphID);
+	 }
+	 
+	 /**
+	  * Plot a circle icon to the function area which is annotated with a char and
+	  * a double value. The color corresponds to the color of the graph with given ID
+	  * 
+	  * @param label
+	  * @param position
+	  * @param graphID
+	  */
+	 public void drawIcon(DPointIcon theIcon, String label, double[] position, int graphID) {
 		 DPointSet popRep;
 		 popRep = new DPointSet();
 		 popRep.addDPoint(new DPoint(position[0], position[1]));
 		 DPointIcon icon = new Chart2DDPointIconText(label);
-		 ((Chart2DDPointIconText)icon).setIcon(new Chart2DDPointIconCircle());
+		 ((Chart2DDPointIconText)icon).setIcon(theIcon);
 		 ((Chart2DDPointIconText)icon).setColor(getGraphPointSet(graphID).getColor());
 		 popRep.setIcon(icon);
 		 addDElement(popRep);
diff --git a/src/eva2/server/go/operators/mutation/InterfaceMutationGenerational.java b/src/eva2/server/go/operators/mutation/InterfaceMutationGenerational.java
index 40529a07..d3aa47ca 100644
--- a/src/eva2/server/go/operators/mutation/InterfaceMutationGenerational.java
+++ b/src/eva2/server/go/operators/mutation/InterfaceMutationGenerational.java
@@ -4,12 +4,34 @@ import eva2.server.go.populations.Population;
 
 /**
  * An interface for a mutation operator which is updated on a generational basis, such as
- * the 1/5-success rule.
+ * the 1/5-success rule. Mind that not all EA use dogmatic selection and thus not all
+ * will inform this interface. So far, only ES and GA will.
  * 
  * @author mkron
  *
  */
 public interface InterfaceMutationGenerational extends InterfaceMutation {
-	public void adaptAfterSelection(Population oldGen, Population selected);
-    public void adaptGenerational(Population selectedPop, Population parentPop, Population newPop, boolean updateSelected);
+	
+	/**
+	 * Perform adaption of the operator based on the selection performed by an EA.
+	 * 
+	 * @param oldPop  the initial population for the developmental step
+	 * @param selectedPop the sup-population selected as parents for the new generation
+	 */
+	public void adaptAfterSelection(Population oldPop, Population selectedPop);
+	
+	/**
+	 * Perform adaption of the operator based on the developmental step performed by an EA. 
+	 * The data provided for this call are the old population, the individuals selected as
+	 * parents, and the new population created from the selected individuals.
+	 * Usually, only the instances within the new population must be adapted. An additional tag 
+	 * indicates whether the instances of the selected population should be adapted as well,
+	 * e.g., if they survive as elite (or in an ES "plus" strategy). 
+	 * 
+	 * @param oldPop the initial population for the developmental step
+	 * @param selectedPop the sup-population selected as parents for the new generation
+	 * @param newPop the new population created by the EA, should already be evaluated
+	 * @param updateSelected if true, the selected population should be adapted as well
+	 */
+	public void adaptGenerational(Population oldPop, Population selectedPop, Population newPop, boolean updateSelected);
 }
diff --git a/src/eva2/server/go/strategies/DifferentialEvolution.java b/src/eva2/server/go/strategies/DifferentialEvolution.java
index 08d5cc5d..3c14c7b9 100644
--- a/src/eva2/server/go/strategies/DifferentialEvolution.java
+++ b/src/eva2/server/go/strategies/DifferentialEvolution.java
@@ -228,7 +228,7 @@ public class DifferentialEvolution implements InterfaceOptimizer, java.io.Serial
             indy = (AbstractEAIndividual)(pop.getEAIndividual(firstParentIndex)).getClone();
             esIndy = (InterfaceDataTypeDouble)indy;
         } catch (java.lang.ClassCastException e) {
-            System.err.println("Differential Evolution currently requires InterfaceESIndividual as basic data type!");
+            EVAERROR.errorMsgOnce("Differential Evolution currently requires InterfaceESIndividual as basic data type!");
             return (AbstractEAIndividual)((AbstractEAIndividual)pop.get(RNG.randomInt(0, pop.size()-1))).getClone();
         }
         double[] nX, vX, oX;