Fix issue #550. Patch by Sebastian Heib.

resources/languages/resources.properties

@@ -195,6 +195,7 @@ service.gui.MSG_DELIVERY_NOT_SUPPORTED=The protocol you are using doesn't suppor
 service.gui.MSG_DELIVERY_INTERNAL_ERROR=An internal error occured. This is most probably a bug. Please report it here: http://www.sip-communicator.org/index.php/Development/BugsAndIssues. Server returned error: {0}
 service.gui.MSG_DELIVERY_UNKNOWN_ERROR=Your message could not be delivered due to the following problem: {0}.
 service.gui.MSG_NOT_DELIVERED=A network problem occured. Please check your network configuration and try again. Server returned error: {0}.
+service.gui.MSG_NOT_POSSIBLE=Messaging is not possible for this contact (it is not supported by the protocol)
 service.gui.MSG_RECEIVED={0} has sent you a message
 service.gui.MSG_SEND_CONNECTION_PROBLEM=You should be connected to be able to send messages.
 service.gui.MULTIPLE_LOGINS=You have logged in more than once with the same account. The following account: User name: {0}, Server name: {1} is currently disconnected.

resources/languages/resources_de.properties

@@ -161,6 +161,7 @@ service.gui.MSG_DELIVERY_NOT_SUPPORTED=Das verwendetet Protokoll kann Nachrichte
 service.gui.MSG_DELIVERY_INTERNAL_ERROR=Ein interner Fehler ist aufgetreten. Dies ist wahrscheinlich ein Bug. Bitte melden Sie ihn unter http://www.sip-communicator.org/index.php/Development/BugsAndIssues
 service.gui.MSG_DELIVERY_UNKNOWN_ERROR=Ihre Nachricht konnte nicht zugestellt werden:
 service.gui.MSG_NOT_DELIVERED=Ein Netzwerkproblem ist aufgetreten.
+service.gui.MSG_NOT_POSSIBLE=Nachrichtenversand ist für diesen Kontakt nicht möglich (dies wird vom verwendeten Protokoll nicht unterstützt).
 service.gui.MSG_RECEIVED={0} hat Ihnen eine Nachricht gesendet.
 service.gui.MSG_SEND_CONNECTION_PROBLEM=Sie sollen verbunden sein, um Nachrichten zu senden.
 service.gui.MULTIPLE_LOGINS=Sie sind mehrfach mit dem selben Konto verbunden. Das Konto User name: {0}, Server name: {1} ist derzeit nicht verbunden.

src/net/java/sip/communicator/impl/gui/main/chat/ChatPanel.java

@@ -155,6 +155,15 @@ public void setChatSession(ChatSession chatSession)
 
             initChatTransportSelectorBox();
 
+            if (!transportSelectorBox.getMenu().isEnabled())
+            {
+                // Show a message to the user that IM is not possible.
+                getChatConversationPanel().appendMessageToEnd("<h5>" +
+                        GuiActivator.getResources().
+                            getI18NString("service.gui.MSG_NOT_POSSIBLE") +
+                        "</h5>");
+            }
+
             //Enables to change the protocol provider by simply pressing the
             // CTRL-P key combination
             ActionMap amap = this.getActionMap();
@@ -947,10 +956,22 @@ private void initChatTransportSelectorBox()
         sendPanel.add(transportSelectorBox, 0);
         sendPanel.add(sendViaLabel, 0);
 
+        updateSendButtonStatus();
+
         this.revalidate();
         this.repaint();
     }
 
+    /**
+     * Sets the send button to the same state (enabled/ disabled) as the
+    * transportSelectorBox.
+    */
+    private void updateSendButtonStatus()
+    {
+        getChatSendPanel().getSendButton().
+                setEnabled(transportSelectorBox.getMenu().isEnabled());
+    }
+
     /**
      * Removes the send via selector box and label.
      */
@@ -1200,11 +1221,13 @@ public void setContactName(ChatContact chatContact, String name)
     public void addChatTransport(ChatTransport chatTransport)
     {
         transportSelectorBox.addChatTransport(chatTransport);
+        updateSendButtonStatus();
     }
 
     public void removeChatTransport(ChatTransport chatTransport)
     {
         transportSelectorBox.removeChatTransport(chatTransport);
+        updateSendButtonStatus();
     }
 
     public void setSelectedChatTransport(ChatTransport chatTransport)

src/net/java/sip/communicator/impl/gui/main/chat/ChatTransportSelectorBox.java

@@ -53,6 +53,10 @@ public ChatTransportSelectorBox(ChatPanel chatPanel,
 
         this.add(menu);
 
+        // as a default disable the menu, it will be enabled as soon as we add
+        // a valid menu item
+        this.menu.setEnabled(false);
+
         Iterator chatTransports = chatSession.getChatTransports();
         while (chatTransports.hasNext())
         {
@@ -61,26 +65,45 @@ public ChatTransportSelectorBox(ChatPanel chatPanel,
             this.addChatTransport(chatTransport);
         }
 
-        this.setSelected(selectedChatTransport);
+        if (this.menu.getItemCount() > 0 &&
+            selectedChatTransport.allowsInstantMessage())
+        {
+            this.setSelected(selectedChatTransport);
+        }
+    }
+
+    /*
+     * Sets the menu to enabled or disabled. The menu is enabled, as soon as it
+     * contains one or more items. If it is empty, it is disabled.
+    */
+    private void updateEnableStatus()
+    {
+        this.menu.setEnabled(this.menu.getItemCount() > 0);
     }
 
     /**
      * Adds the given chat transport to the "send via" menu.
+     * Only add those that support IM.
      *
      * @param chatTransport The chat transport to add.
      */
     public void addChatTransport(ChatTransport chatTransport)
     {
-        Image img = createTransportStatusImage(chatTransport);
+        if (chatTransport.allowsInstantMessage())
+        {
+            Image img = createTransportStatusImage(chatTransport);
+
+            JMenuItem menuItem = new JMenuItem(
+                        chatTransport.getName(),
+                        new ImageIcon(img));
 
-        JMenuItem menuItem = new JMenuItem(
-                    chatTransport.getName(),
-                    new ImageIcon(img));
+            menuItem.addActionListener(this);
+            this.transportMenuItems.put(chatTransport, menuItem);
 
-        menuItem.addActionListener(this);
-        this.transportMenuItems.put(chatTransport, menuItem);
+            this.menu.add(menuItem);
 
-        this.menu.add(menuItem);
+            updateEnableStatus();
+        }
     }
 
     /**
@@ -94,6 +117,8 @@ public void removeChatTransport(ChatTransport chatTransport)
     {
         this.menu.remove(transportMenuItems.get(chatTransport));
         this.transportMenuItems.remove(chatTransport);
+
+        updateEnableStatus();
     }
 
     /**

src/net/java/sip/communicator/impl/protocol/sip/ProtocolProviderServiceSipImpl.java

@@ -459,19 +459,22 @@ protected void initialize(String    sipAddress,
                 OperationSetPresence.class.getName()
                 , opSetPersPresence);
 
-            // init instant messaging
-            OperationSetBasicInstantMessagingSipImpl opSetBasicIM =
-                new OperationSetBasicInstantMessagingSipImpl(this);
-            this.supportedOperationSets.put(
-                OperationSetBasicInstantMessaging.class.getName(),
-                opSetBasicIM);
-
-            // init typing notifications
-            OperationSetTypingNotificationsSipImpl opSetTyping =
-                new OperationSetTypingNotificationsSipImpl(this, opSetBasicIM);
-            this.supportedOperationSets.put(
-                OperationSetTypingNotifications.class.getName(),
-                opSetTyping);
+            if (enablePresence)
+            {
+                // init instant messaging
+                OperationSetBasicInstantMessagingSipImpl opSetBasicIM =
+                    new OperationSetBasicInstantMessagingSipImpl(this);
+                this.supportedOperationSets.put(
+                    OperationSetBasicInstantMessaging.class.getName(),
+                    opSetBasicIM);
+
+                // init typing notifications
+                OperationSetTypingNotificationsSipImpl opSetTyping =
+                    new OperationSetTypingNotificationsSipImpl(this, opSetBasicIM);
+                this.supportedOperationSets.put(
+                    OperationSetTypingNotifications.class.getName(),
+                    opSetTyping);
+            }
 
             // OperationSetVideoTelephony
             supportedOperationSets.put(