synchronize renderer methods - you don't really want to add an item

 while you are rendering the items list

src/com/fluendo/jtiger/Renderer.java

@@ -30,7 +30,7 @@ public class Renderer {
   /**
    * Add a new event to the renderer.
    */
-  public void add(com.fluendo.jkate.Event ev) {
+  public synchronized void add(com.fluendo.jkate.Event ev) {
     items.addElement(new Item(ev));
     dirty = true;
   }
@@ -39,7 +39,7 @@ public class Renderer {
    * Update the renderer, and all the events it tracks.
    * Returns 1 if there is nothing to draw, as an optimization
    */
-  public int update(Component c, Dimension d, double t) {
+  public synchronized int update(Component c, Dimension d, double t) {
     for (int n=0; n<items.size(); ++n) {
       boolean ret = ((Item)items.elementAt(n)).update(c, d, t);
       if (!ret) {
@@ -61,7 +61,7 @@ public class Renderer {
   /**
    * Renders onto the given image.
    */
-  public Image render(Component c, Image img) {
+  public synchronized Image render(Component c, Image img) {
     /* there used to be some non copying code using BufferedImage, but that's not in SDK 1.1, so we do it the slow way */
     Image copy = c.createImage(img.getWidth(null), img.getHeight(null));
     Graphics g = copy.getGraphics();
@@ -81,12 +81,12 @@ public class Renderer {
   /**
    * Flushes all events.
    */
-  public void flush() {
+  public synchronized void flush() {
     items.removeAllElements();
     dirty = true;
   }
 
-  public boolean isDirty() {
+  public synchronized boolean isDirty() {
     return dirty;
   }
 }