=== modified file 'src/com/goldencode/p2j/ui/client/driver/web/res/p2j.socket.js'
--- src/com/goldencode/p2j/ui/client/driver/web/res/p2j.socket.js	2015-08-10 20:53:46 +0000
+++ src/com/goldencode/p2j/ui/client/driver/web/res/p2j.socket.js	2015-08-11 21:58:00 +0000
@@ -309,7 +309,13 @@
                   case 0x8B:
                      // destroy top-level or child window
                      var id = me.readInt32BinaryMessage(message, 1);
-                     p2j.screen.destroyWindow(id);
+                     var numberImages = me.readInt32BinaryMessage(message, 5);
+                     var images = [];
+                     for ( var i = 0; i < numberImages; i++)
+                     {
+                        images[i] = me.readInt32BinaryMessage(message, 9 + i << 2);
+                     }
+                     p2j.screen.destroyWindow(id, images);
                      break;
                   case 0x8C:
                      // change visibility for top-level or child window

=== modified file 'src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebDriver.java'
--- src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebDriver.java	2015-08-10 20:53:46 +0000
+++ src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebDriver.java	2015-08-11 21:40:08 +0000
@@ -22,11 +22,11 @@
 
 // TODO: remove this, it is there to allow compilation
 import java.awt.Font;
+import java.util.HashMap;
 import java.util.HashSet;
 // don't import the entire logging package as it has naming conflicts with jetty
 import java.util.logging.Level;
 import java.util.logging.Logger;
-
 import java.util.*;
 
 import org.eclipse.jetty.util.resource.*;
@@ -80,8 +80,11 @@
    /** Virtual screen for drawing in a memory */
    private VirtualScreen virtualScreen;
    
-   /** Images loaded by a client. */
-   private final HashSet<Integer> loadedImages;
+   /** Image usages is a mapping of an image loaded by a client to its owner windows. */
+   private final Map<Integer, Set<Integer> > imageUsages;
+   
+   /** Owned images is a mapping of a window to its owned images. */
+   private final Map<Integer, Set<Integer> > ownedImages;
    
    /** A cache of font metrics objects, by their remote font ID. */
    private Map<Integer, FontMetricsHelper> fontMetricsCache = new HashMap<>();
@@ -107,7 +110,8 @@
       });
       
       this.config = config;
-      this.loadedImages = new HashSet<Integer>();
+      this.imageUsages = new HashMap<Integer, Set<Integer>>();
+      this.ownedImages = new HashMap<Integer, Set<Integer>>();
    }
    
    /**
@@ -196,16 +200,77 @@
    }
    
    /**
+    * Returns its virtual screen that represents the physical screen in a memory
+    * using a sRGB pixel model.
     * 
-    * @return
+    * @return The virtual screen to draw images in a memory.
     */
    public VirtualScreen getVirtualScreen()
    {
       return virtualScreen;
    }
    
-   public boolean addImage(int imageHash) {
-      return this.loadedImages.add(imageHash);
+   /**
+    * Register a usage of the given image by the given window.
+    * 
+    * @param    imageHash
+    *           The image hash id.
+    * @param    windowId
+    *           The window id.
+    * 
+    * @return   True iff it is the first usage of the given image.
+    */
+   public boolean addImageUsage(int imageHash, int windowId) {
+      boolean newLoadedImage = false;
+      
+      Set<Integer> usages = imageUsages.get(imageHash);
+      if (usages == null)
+      {
+         usages = new HashSet<Integer>();
+         imageUsages.put(imageHash, usages);
+         newLoadedImage = true;
+      }
+      usages.add(windowId);
+      
+      Set<Integer> images = ownedImages.get(windowId);
+      if (images == null)
+      {
+         images = new HashSet<Integer>();
+         ownedImages.put(windowId, images);
+      }
+      images.add(imageHash);
+      
+      return newLoadedImage;
+   }
+   
+   /**
+    * Returns all unused images. Removes the given window from all image usages.
+    * 
+    * @param    windowId
+    *           The window id.
+    * 
+    * @return The set of all unused images.
+    */
+   public Set<Integer> removeUnusedImages(int windowId) {
+      Set<Integer> imagesToRemove = new HashSet<Integer>();
+      Set<Integer> images = ownedImages.remove(windowId);
+      if (images != null && !images.isEmpty())
+      {
+         for (Integer imageHash : images)
+         {
+            Set<Integer> usages = imageUsages.get(imageHash);
+            if (usages.remove(windowId))
+            {
+               if (usages.isEmpty())
+               {
+                  imagesToRemove.add(imageHash);
+                  imageUsages.remove(imageHash);
+               }
+            }
+         }
+      }
+      
+      return imagesToRemove;
    }
    
    /**

=== modified file 'src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebEmulatedWindow.java'
--- src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebEmulatedWindow.java	2015-08-10 22:08:54 +0000
+++ src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebEmulatedWindow.java	2015-08-11 21:40:08 +0000
@@ -21,6 +21,8 @@
 package com.goldencode.p2j.ui.client.gui.driver.web;
 
 import java.awt.image.BufferedImage;
+import java.util.Set;
+
 
 import com.goldencode.p2j.ui.client.*;
 import com.goldencode.p2j.ui.client.gui.driver.*;
@@ -87,7 +89,9 @@
    @Override
    public void quit()
    {
-      websock.destroyWindow(windowId);
+      Set<Integer> imagesToRemove = webdriver.removeUnusedImages(windowId);
+      
+      websock.destroyWindow(windowId, imagesToRemove.toArray(new Integer[imagesToRemove.size()]));
    }
 
    /**
@@ -397,7 +401,7 @@
             int imageHash = wrappedImage.getImage().hashCode();
             ImageEncoding encoding;
             byte[] encodedImage;
-            if (webdriver.addImage(imageHash))
+            if (webdriver.addImageUsage(imageHash, windowId))
             {
                encoding = ImageEncoding.RAW;
                virtualScreen.drawImage(wrappedImage, ps.x, ps.y);

=== modified file 'src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebSocket.java'
--- src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebSocket.java	2015-08-10 20:53:46 +0000
+++ src/com/goldencode/p2j/ui/client/gui/driver/web/GuiWebSocket.java	2015-08-11 21:51:53 +0000
@@ -132,10 +132,23 @@
     *
     * @param    id
     *           The window id to destroy.
+    * @param    cashedImages
+    *           The array of client cached images to remove.
     */
-   public void destroyWindow(int id)
+   public void destroyWindow(int id, Integer[] cachedImages)
    {
-      sendBinaryMessage(MSG_DESTROY_WINDOW, id);
+      byte[] message = new byte[9 + cachedImages.length << 2];
+      
+      message[0] = MSG_DESTROY_WINDOW;
+      writeMessageInt32(message, 1, id);
+      writeMessageInt32(message, 5, cachedImages.length);
+      int idx = 9;
+      for(Integer imageHash : cachedImages)
+      {
+         writeMessageInt32(message, idx, imageHash);
+         idx += 4;
+      }
+      sendBinaryMessage(message);
    }
    
    /**

=== modified file 'src/com/goldencode/p2j/ui/client/gui/driver/web/res/p2j.screen.js'
--- src/com/goldencode/p2j/ui/client/gui/driver/web/res/p2j.screen.js	2015-08-10 22:08:54 +0000
+++ src/com/goldencode/p2j/ui/client/gui/driver/web/res/p2j.screen.js	2015-08-11 22:03:51 +0000
@@ -517,10 +517,12 @@
                var pixelsInBytes = width * height * 4;
                var imgData;
                var imgDataOffset;
-               if(loadedImages.has(key)) {
+               if(loadedImages.has(key))
+               {
                   imgData = loadedImages.get(key);
                   imgDataOffset = 0;
-               } else {
+               } else
+               {
                   imgData = message;
                   imgDataOffset = idx + 22;
                   loadedImages.set(key, message.subarray(imgDataOffset, imgDataOffset + pixelsInBytes));
@@ -822,7 +824,20 @@
    }                         
    
    /**
+    * It draws an image on the canvas.
     * 
+    * @param    {Number} x
+    *           X coordinate of the top left corner.
+    * @param    {Number} y
+    *           Y coordinate of the top left corner.
+    * @param    {Number} width
+    *           Width of the image in pixels.
+    * @param    {Number} height
+    *           Height of the image in pixels.
+    * @param    {Array} imgData
+    *           The image data array contains the encoded image started from the given offset.
+    * @param    {Number} imgDataOffset
+    *           The offset of the encoded image data.
     */
    function drawImage(x, y, width, height, imgData, imgDataOffset)
    {
@@ -1256,8 +1271,10 @@
     *
     * @param    wid
     *           The window id by which this window can be uniquely identified.
+    * @param    images
+    *           The cached images to remove.
     */
-   me.destroyWindow = function(wid)
+   me.destroyWindow = function(wid, images)
    {
       if (!isValidWindowId(wid))
       {
@@ -1274,7 +1291,10 @@
       var win = getWindow(wid);
       
       win.cleanup();
-      
+      for (var image in images)
+      {
+         loadedImages.delete(image);
+      }
       // remove from our window list
       delete winlist[wid];
    }