Add a base class for events with a WindowModel source.

For #662, it makes sense to have a standard way to
get the source from events we may wish to filter.

This introduces a SourcedEvent interface, and adapts classes
to use it.

src/com/dmdirc/Server.java

 
     @Handler
     private void handleClose(final FrameClosingEvent event) {
-        if (event.getContainer() == windowModel) {
+        if (event.getSource() == windowModel) {
             synchronized (myStateLock) {
                 eventHandler.unregisterCallbacks();
                 windowModel.getConfigManager().removeListener(configListener);

src/com/dmdirc/ServerManager.java

 
     @Handler
     void handleWindowClosing(final FrameClosingEvent event) {
-        if (event.getContainer() instanceof Server) {
-            unregisterServer((Server) event.getContainer());
+        if (event.getSource() instanceof Server) {
+            unregisterServer((Server) event.getSource());
         }
     }
 

src/com/dmdirc/events/DisplayableEvent.java

 
 package com.dmdirc.events;
 
-import com.dmdirc.interfaces.WindowModel;
-
 import java.time.LocalDateTime;
 import java.util.Optional;
 
 /**
  * Describes an event which is rendered in the client to the user.
  */
-public interface DisplayableEvent {
+public interface DisplayableEvent extends SourcedEvent {
 
     /**
      * Sets a property relating to how this event should be displayed.
      */
     LocalDateTime getTimestamp();
 
-    /**
-     * Gets the source of the displayable event.
-     */
-    WindowModel getSource();
-
 }

src/com/dmdirc/events/FrameEvent.java

 /**
  * Base class for window related events in the client.
  */
-public abstract class FrameEvent extends DMDircEvent {
+public abstract class FrameEvent extends DMDircEvent implements SourcedEvent {
 
-    private final WindowModel container;
+    private final WindowModel source;
 
-    public FrameEvent(final WindowModel container) {
-        this.container = container;
+    public FrameEvent(final WindowModel source) {
+        this.source = source;
     }
 
-    public WindowModel getContainer() {
-        return container;
+    @Override
+    public WindowModel getSource() {
+        return source;
     }
+
 }

src/com/dmdirc/events/SourcedEvent.java

+/*
+ * Copyright (c) 2006-2015 DMDirc Developers
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.events;
+
+import com.dmdirc.interfaces.WindowModel;
+
+/**
+ * An event that is attached to a {@link WindowModel} source.
+ */
+public interface SourcedEvent {
+
+    /**
+     * Gets the source of the event.
+     */
+    WindowModel getSource();
+
+}

src/com/dmdirc/events/UnreadStatusChangedEvent.java

 /**
  * Event raised when the unread status of a window has changed.
  */
-public class UnreadStatusChangedEvent extends DMDircEvent {
+public class UnreadStatusChangedEvent extends DMDircEvent implements SourcedEvent {
 
     private final WindowModel source;
     private final UnreadStatusManager manager;
         this.unreadCount = unreadCount;
     }
 
+    @Override
     public WindowModel getSource() {
         return source;
     }

src/com/dmdirc/ui/WindowManager.java

 
     @Handler
     public void frameClosing(final FrameClosingEvent event) {
-        removeWindow(event.getContainer());
+        removeWindow(event.getSource());
     }
 
 }

src/com/dmdirc/ui/input/InputHandler.java

 
     @Handler
     void parentClosing(final FrameClosingEvent event) {
-        if (event.getContainer().equals(parentWindow)) {
+        if (event.getSource().equals(parentWindow)) {
             executorService.shutdown();
             eventBus.unsubscribe(this);
         }