[growl integration] New methods for the systray service:

- getPreferenceIndex() which indicates how many features the handler implements
- selectBestPopupMessageHandler() which selects the best message popup handler according to the one available

Updated the unit tests accordingly.

src/net/java/sip/communicator/service/systray/PopupMessageHandler.java

@@ -43,6 +43,20 @@ public interface PopupMessageHandler
      * @param popupMessage the message to show
      */
     public void showPopupMessage(PopupMessage popupMessage);
+    
+    /**
+     * Returns a preference index, which indicates how many features the handler 
+     * implements. Implementer should calculate preference index by adding "1" 
+     * for each of the the following features that the implementation supports: 
+     * 
+     * 1) showing images
+     * 2) detecting clicks
+     * 3) being able to match a click to a message
+     * 4) using a native popup mechanism
+     * 
+     * @returns an integer representing preference index of this popup handler
+     */
+    public int getPreferenceIndex();
 
     /**
      * Returns a readable description of this popup handler. It is expected

src/net/java/sip/communicator/service/systray/SystrayService.java

@@ -103,4 +103,9 @@ public PopupMessageHandler setActivePopupMessageHandler(
      * @param imageType the type of the image to set
      */
     public void setSystrayIcon(int imageType);
+
+    /**
+     * Selects the best available popup message handler
+     */
+    public void selectBestPopupMessageHandler();
 }

test/net/java/sip/communicator/slick/popupmessagehandler/TestPopupMessageHandler.java

@@ -161,5 +161,13 @@ public void showPopupMessage(PopupMessage popupMsg)
             // is it the expected handler which is handling it ?
             assertEquals(handler2, this);
         }
+        
+        /**
+         * implements <tt>getPreferenceIndex</tt> from <tt>PopupMessageHandler</tt>
+         */
+        public int getPreferenceIndex()
+        {
+            return 0;
+        }
     }
 }