diff --git a/src/org/hwo/ui/JTimeSpanEditor.java b/src/org/hwo/ui/JTimeSpanEditor.java
index 8d8ee24..2aa4902 100644
--- a/src/org/hwo/ui/JTimeSpanEditor.java
+++ b/src/org/hwo/ui/JTimeSpanEditor.java
@@ -14,6 +14,9 @@ import java.util.LinkedList;
 import java.util.List;
 
 import javax.swing.JLabel;
+import javax.swing.JCheckBox;
+import java.awt.event.ActionListener;
+import java.awt.event.ActionEvent;
 
 public class JTimeSpanEditor extends JComponent implements FocusListener {
 	private JSpinner spDays;
@@ -26,32 +29,45 @@ public class JTimeSpanEditor extends JComponent implements FocusListener {
 	
 	private List<FocusListener> focusListeners;
 	private List<Component> components;
+	private JCheckBox cbNull;
 	
 	public JTimeSpanEditor() {
 		this.focusListeners = new LinkedList<FocusListener>();
 		
 		GridBagLayout gridBagLayout = new GridBagLayout();
-		gridBagLayout.columnWidths = new int[] {0, 0, 0, 0, 0, 0, 0};
+		gridBagLayout.columnWidths = new int[] {0, 0, 0, 0, 0, 0, 0, 0};
 		gridBagLayout.rowHeights = new int[]{0, 0};
-		gridBagLayout.columnWeights = new double[]{1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0};
+		gridBagLayout.columnWeights = new double[]{0.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0};
 		gridBagLayout.rowWeights = new double[]{1.0, Double.MIN_VALUE};
 		setLayout(gridBagLayout);
 		
 		spDays = new JSpinner();
 		spDays.addFocusListener(this);
 		spDays.getEditor().addFocusListener(this);
+		
+		cbNull = new JCheckBox("");
+		cbNull.addActionListener(new ActionListener() {
+			public void actionPerformed(ActionEvent arg0) {
+				enableControls(cbNull.isSelected());
+			}
+		});
+		GridBagConstraints gbc_cbNull = new GridBagConstraints();
+		gbc_cbNull.insets = new Insets(0, 0, 0, 5);
+		gbc_cbNull.gridx = 0;
+		gbc_cbNull.gridy = 0;
+		add(cbNull, gbc_cbNull);
 		spDays.setModel(new SpinnerNumberModel(0, 0, 366, 1));
 		GridBagConstraints gbc_spDays = new GridBagConstraints();
 		gbc_spDays.fill = GridBagConstraints.BOTH;
 		gbc_spDays.insets = new Insets(0, 0, 0, 5);
-		gbc_spDays.gridx = 0;
+		gbc_spDays.gridx = 1;
 		gbc_spDays.gridy = 0;
 		add(spDays, gbc_spDays);
 		
 		lblD = new JLabel("d");
 		GridBagConstraints gbc_lblD = new GridBagConstraints();
 		gbc_lblD.insets = new Insets(0, 0, 0, 5);
-		gbc_lblD.gridx = 1;
+		gbc_lblD.gridx = 2;
 		gbc_lblD.gridy = 0;
 		add(lblD, gbc_lblD);
 
@@ -63,14 +79,14 @@ public class JTimeSpanEditor extends JComponent implements FocusListener {
 		GridBagConstraints gbc_spHours = new GridBagConstraints();
 		gbc_spHours.fill = GridBagConstraints.BOTH;
 		gbc_spHours.insets = new Insets(0, 0, 0, 5);
-		gbc_spHours.gridx = 2;
+		gbc_spHours.gridx = 3;
 		gbc_spHours.gridy = 0;
 		add(spHours, gbc_spHours);
 		
 		lblNewLabel = new JLabel(":");
 		GridBagConstraints gbc_lblNewLabel = new GridBagConstraints();
 		gbc_lblNewLabel.insets = new Insets(0, 0, 0, 5);
-		gbc_lblNewLabel.gridx = 3;
+		gbc_lblNewLabel.gridx = 4;
 		gbc_lblNewLabel.gridy = 0;
 		add(lblNewLabel, gbc_lblNewLabel);
 
@@ -81,14 +97,14 @@ public class JTimeSpanEditor extends JComponent implements FocusListener {
 		GridBagConstraints gbc_spMinutes = new GridBagConstraints();
 		gbc_spMinutes.fill = GridBagConstraints.BOTH;
 		gbc_spMinutes.insets = new Insets(0, 0, 0, 5);
-		gbc_spMinutes.gridx = 4;
+		gbc_spMinutes.gridx = 5;
 		gbc_spMinutes.gridy = 0;
 		add(spMinutes, gbc_spMinutes);
 		
 		label = new JLabel(":");
 		GridBagConstraints gbc_label = new GridBagConstraints();
 		gbc_label.insets = new Insets(0, 0, 0, 5);
-		gbc_label.gridx = 5;
+		gbc_label.gridx = 6;
 		gbc_label.gridy = 0;
 		add(label, gbc_label);
 
@@ -98,7 +114,7 @@ public class JTimeSpanEditor extends JComponent implements FocusListener {
 		spSeconds.setModel(new SpinnerNumberModel(0, 0, 59, 1));
 		GridBagConstraints gbc_spSeconds = new GridBagConstraints();
 		gbc_spSeconds.fill = GridBagConstraints.BOTH;
-		gbc_spSeconds.gridx = 6;
+		gbc_spSeconds.gridx = 7;
 		gbc_spSeconds.gridy = 0;
 		add(spSeconds, gbc_spSeconds);
 
@@ -148,20 +164,21 @@ public class JTimeSpanEditor extends JComponent implements FocusListener {
 				;
 	}
 	
+	private void enableControls(Boolean enable){
+		spSeconds.setEnabled(enable);
+		spMinutes.setEnabled(enable);
+		spHours.setEnabled(enable);
+		spDays.setEnabled(enable);
+	}
+	
 	public void setValue(Integer seconds){
 		Integer mod = seconds;
 		
 		if (mod == null){
-			spSeconds.setEnabled(false);
-			spMinutes.setEnabled(false);
-			spHours.setEnabled(false);
-			spDays.setEnabled(false);
+			cbNull.setSelected(false);
 		} else {
-			spSeconds.setEnabled(true);
-			spMinutes.setEnabled(true);
-			spHours.setEnabled(true);
-			spDays.setEnabled(true);
-
+			cbNull.setSelected(true);
+			
 			if (spDays.isVisible())
 				spDays.setValue(mod / 86400);
 			
@@ -174,6 +191,22 @@ public class JTimeSpanEditor extends JComponent implements FocusListener {
 		}		
 	}
 	
+	public String getValueAsString(){
+		return getValueAsString(getValue());
+	}
+
+	public String getValueAsString(int timeSpan){
+		int hours,minutes,seconds;
+		
+		hours = timeSpan / 3600;
+		timeSpan %= 3600;
+		minutes = timeSpan / 60;
+		timeSpan %= 60;
+		seconds = timeSpan;
+		
+		return String.format("%d:%02d:%02d", hours,minutes,seconds);
+	}
+	
 	public boolean isDaysEnabled(){
 		return spDays.isVisible();
 	}