Complete UpButt.

src/main/data/StockEntry.java

@@ -14,12 +14,17 @@ public class StockEntry {
         this.stype = stype;
     }
 
-    public void update() {
+    public boolean update() {
+        boolean changed = false;
         updating = true;
         double[] result = this.stype.update(this.identifier);
+        if ((result[0] != price) || (result[1] != change)) {
+            changed = true;
+        }
         this.price = result[0];
         this.change = result[1];
         updating = false;
+        return changed;
     }
 
     public String getTypeName() {

src/main/data/WatchList.java

@@ -133,13 +133,19 @@ public class WatchList extends Observable implements Load,Save {
 
     public void updateList() {
         Iterator watchit = iterator();
+        boolean changed = false;
         while (watchit.hasNext()) {
             Map.Entry entry = (Map.Entry)watchit.next();
             StockEntry sentry = (StockEntry)entry.getValue();
+            if (!changed) {
+                changed = changed || sentry.update();
+            }
             sentry.update();
         }
-        setChanged();
-        notifyObservers(new Wevent(Etype.UPDATE));
+        if (changed) {
+            setChanged();
+            notifyObservers(new Wevent(Etype.UPDATE));
+        }
     }
 
     public class Wevent {

src/main/ui/guicomp/UpButt.java

@@ -11,12 +11,17 @@ public class UpButt extends JButton {
     public UpButt(WatchList wlist) {
         super("Update");
         addActionListener(new UpButtList());
-	this.wlist = wlist;
+        this.wlist = wlist;
     }
 
     private class UpButtList implements ActionListener {
         public void actionPerformed(ActionEvent e) {
-            //XXX Update WatchList
+            new Thread(new Runnable() {
+                @Override
+                public void run() {
+                    wlist.updateList();
+                }
+            }).start();
         }
     }
 }