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diff --git a/src/jcgp/gui/settings/parameters/GUIParameter.java b/src/jcgp/gui/settings/parameters/GUIParameter.java
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+++ b/src/jcgp/gui/settings/parameters/GUIParameter.java
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+package jcgp.gui.settings.parameters;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import javafx.application.Platform;
+import javafx.beans.value.ChangeListener;
+import javafx.beans.value.ObservableValue;
+import javafx.geometry.Pos;
+import javafx.scene.control.Control;
+import javafx.scene.control.Label;
+import javafx.scene.control.Tooltip;
+import javafx.scene.layout.HBox;
+import jcgp.backend.parameters.BooleanParameter;
+import jcgp.backend.parameters.DoubleParameter;
+import jcgp.backend.parameters.IntegerParameter;
+import jcgp.backend.parameters.Parameter;
+import jcgp.backend.parameters.ParameterStatus;
+import jcgp.gui.settings.SettingsPane;
+
+/**
+ * 
+ * This is the base class for all @code{GUIParameter}s. Using the factory method @code{GUIParameter.create()}
+ * generates an appropriate instance of this class for the specified parameter.
+ * <br><br>
+ * A @code{GUIParameter} is an @code{HBox} containing a @code{Text} for the parameter name 
+ * and a @code{Control} for interaction.
+ * It stores an instance of its associated @code{Parameter} object and also contains a @code{Tooltip} for 
+ * displaying status information.
+ * <br><br>
+ * Monitor parameters are updated automatically and have their @code{Control} disabled so
+ * that no changes can be made via the GUI.
+ * Non-monitor parameters are updated automatically as well, but may be changed by the user
+ * if the program is not evolving.
+ * 
+ * @see Parameter
+ * @author Eduardo Pedroni
+ * @param <T> the parameter data type
+ */
+public abstract class GUIParameter<T> extends HBox {
+	
+	private Label name;
+	private Control valueControl;
+	
+	protected SettingsPane settingsPane;
+	protected Tooltip tooltip;
+	protected Parameter<T> parameter;
+	
+	/** This is the lock used to prevent more than one update task to be scheduled
+	 *  at the same time on the same GUIParameter. */
+	private AtomicBoolean updateLock = new AtomicBoolean(false);
+	
+	/**
+	 * This value is used to assert whether the control has changed values since 
+	 * the program last ran. Therefore, it is updated whenever a generation occurs
+	 * or the experiment is reset.
+	 */
+	private T referenceValue;
+	
+	/**
+	 * This protected template constructor contains the common elements to all
+	 * @code{GUIParameter}s and should be invoked by any subclasses using @code{super()}. It
+	 * defers the creation of the parameter {@code Control} object to the subclass
+	 * currently being built (which in turn is defined by the factory method).
+	 * 
+	 * @param parameter a @code{Parameter} for which to generate a @code{GUIParameter}.
+	 * @param sp a reference to the @code{SettingsPane}.
+	 */
+	protected GUIParameter(Parameter<T> parameter, final SettingsPane settingsPane) {
+		this.parameter = parameter;
+		this.referenceValue = parameter.get();
+		
+		this.settingsPane = settingsPane;
+		
+		setAlignment(Pos.CENTER_LEFT);
+		setSpacing(5);
+		
+		name = new Label(parameter.toString());
+		// set text width to half of the total width of the GUIParameter
+		name.prefWidthProperty().bind(widthProperty().divide(2));
+		
+		// the tooltip is the hover-over label containing status information, when appropriate
+		tooltip = new Tooltip();
+		tooltip.setSkin(null);
+		
+		valueControl = makeControl();
+		
+		// if the parameter is a monitor, it should be permanently disabled
+		valueControl.setDisable(parameter.isMonitor());
+		
+		// bind to parameter value property in a thread-safe way
+		makeThreadSafeBinding();
+		
+		// if parameter is not a monitor, make sure the control is constrained appropriately
+		if (!parameter.isMonitor()) {
+			setControlListeners();
+		}
+		
+		getChildren().addAll(name, valueControl);
+	}
+	
+	/**
+	 * Factory method to create @code{GUIParameter}s from @code{Parameter}s. 
+	 * Use this to create an appropriate @code{GUIParameter} from any instance of @code{Parameter},
+	 * rather than manually downcasting the @code{Parameter} object every time.
+	 * 
+	 * @param parameter a parameter for which to generate a @code{GUIParameter}.
+	 * @param sp a reference to the @code{SettingsPane}.
+	 * @return an appropriate instance of @code{GUIParameter}.
+	 */
+	public static GUIParameter<?> create(Parameter<?> parameter, SettingsPane sp) {
+		if (parameter instanceof IntegerParameter) {
+			return new GUIIntegerParameter((IntegerParameter) parameter, sp);
+		} else if (parameter instanceof DoubleParameter) {
+			return new GUIDoubleParameter((DoubleParameter) parameter, sp);
+		} else if (parameter instanceof BooleanParameter) {
+			return new GUIBooleanParameter((BooleanParameter) parameter, sp);
+		} else {
+			throw new ClassCastException("No GUIParameter subclass exists for argument of type " + parameter.getClass());
+		}
+	}
+
+	/**
+	 * Parameters are intended to communicate information from the experiment
+	 * to the GUI. Since the experiment runs on a separate threads and it is illegal
+	 * to modify JavaFX objects from outside the JavaFX Application thread, this
+	 * special ChangeListener updates the GUIParameter in a safe way.
+	 * <br><br>
+	 * Note that this is applied to all parameters regardless of whether they are 
+	 * monitors or not; the only difference between monitor and non-monitor parameters
+	 * is that monitor parameters cannot be modified from the GUI.
+	 */
+	private void makeThreadSafeBinding() {
+		parameter.valueProperty().addListener(new ChangeListener<Object>() {
+			@Override
+			public void changed(
+					ObservableValue<? extends Object> observable,
+					Object oldValue, Object newValue) {
+				// only do this if the experiment is running
+				if (settingsPane.isExperimentRunning() || !isFocused()) {
+					/* here's the catch - atomically get the lock state and set it to true
+					 * the lock will only be false again when the runnable is finished executing, 
+					 * preventing multiple runnables to concurrently update the same GUIParameter
+					 */
+					if (!updateLock.getAndSet(true)) {
+						Platform.runLater(new Runnable() {
+							@Override
+							public void run() {
+								refreshValue();
+								updateLock.set(false);
+							}
+						});
+					}
+				}
+			}
+		});
+	}
+	
+	/**
+	 * @return true if the current value of the parameter does not prevent the 
+	 * experiment from running.
+	 */
+	public boolean isValid() {
+		return parameter.getStatus() != ParameterStatus.INVALID;
+	}
+	
+	/**
+	 * Force the parameter to validate its current value, and apply the associated
+	 * style to the @code{GUIParameter}.
+	 */
+	public void validate() {
+		parameter.validate(parameter.get());
+		setValidityStyle();
+	}
+	
+	/**
+	 * Certain parameter changes might require the experiment to be reset, either
+	 * because the parameter is critical or because its status requires a reset.
+	 * 
+	 * @return true if an experiment reset is required due to this parameter changing.
+	 */
+	public boolean requiresReset() {
+		return (parameter.isCritical() && !parameter.get().equals(referenceValue))
+				|| parameter.getStatus() == ParameterStatus.WARNING_RESET;
+	}
+	
+	/**
+	 * Set the current parameter value as the reference value of the @code{GUIParameter}.
+	 * The new reference value will be used to determine the validity of the parameter, 
+	 * should its value change.
+	 */
+	public void applyValue() {
+		referenceValue = parameter.get();
+	}
+	
+	/* 
+	 * The following prototypes are instance-dependent and are called from
+	 * GUIParameter() as necessary.
+	 */
+	/**
+	 * This method returns the @code{Control} object used to control the parameter.
+	 * <br><br>
+	 * Implementations of @code{GUIParameter} must override this method and return 
+	 * a @code{Control} appropriate to the type of parameter. This will typically be
+	 * done by referencing the protected field @code{GUIParameter.parameter}.
+	 * 
+	 * @return the Control object to be added to the GUIParameter.
+	 */
+	protected abstract Control makeControl();
+	
+	/**
+	 * Adds the necessary handlers to the @code{Control} object in order to modify
+	 * the underlying parameter. This will typically consist of filtering key
+	 * presses to ensure no invalid characters are inserted, applying the new 
+	 * value to the underlying parameter and revalidating the parameters to
+	 * reflect the changes made.
+	 */
+	protected abstract void setControlListeners();
+	
+	/**
+	 * This method is called to style the @code{GUIParameter} according to the status of
+	 * the parameter, which can be obtained with @code{parameter.getStatus()}. While the
+	 * subclass is free to style itself in any way, the CSS strings defined here 
+	 * (INVALID_PARAMETER_STYLE, WARNING_PARAMETER_STYLE, VALID_PARAMETER_STYLE)
+	 * provide a way to keep the GUI consistent.
+	 * 
+	 * @see ParameterStatus
+	 */
+	protected abstract void setValidityStyle();
+	
+	/**
+	 * Update the control so it shows the correct value of the parameter. This method
+	 * is used exclusively by the thread-safe binding created if the module is a monitor.
+	 */
+	protected abstract void refreshValue();
+}