diff --git a/TODO b/TODO
index d7beca0..d2e5246 100644
--- a/TODO
+++ b/TODO
@@ -11,8 +11,6 @@
 Not easily feasible since newmailalerts are hard-coded
 http://mxr.mozilla.org/comm-central/find?string=content/newmailalert
 
-* make multi-platform. At least have js-ctypes library call dependant on OS detection. (best would be to have the OS-dependant modules loaded at startup) 
-
 * convert to a https://developer.mozilla.org/en/Extensions/Bootstrapped_extensions
 
 see ../restartless-restart-ffext/ and
diff --git a/src/chrome/skin/newmail.png b/src/chrome/skin/blank-icon.png
similarity index 100%
rename from src/chrome/skin/newmail.png
rename to src/chrome/skin/blank-icon.png
diff --git a/src/modules/FiretrayHandler.jsm b/src/modules/FiretrayHandler.jsm
index 6c7954b..6b2ae51 100644
--- a/src/modules/FiretrayHandler.jsm
+++ b/src/modules/FiretrayHandler.jsm
@@ -20,7 +20,7 @@ if ("undefined" == typeof(firetray)) {
 };
 
 /**
- * Singleton object for tray icon management
+ * Singleton object and abstraction for tray icon management.
  */
 // NOTE: modules work outside of the window scope. Unlike scripts in the
 // chrome, modules don't have access to objects such as window, document, or
@@ -28,11 +28,92 @@ if ("undefined" == typeof(firetray)) {
 // (https://developer.mozilla.org/en/XUL_School/JavaScript_Object_Management)
 firetray.Handler = {
   initialized: false,
+  appName: null,
+  FILENAME_DEFAULT: null,
+  FILENAME_SUFFIX: "32.png",
+  FILENAME_BLANK: null,
+  FILENAME_NEWMAIL: null,
+  runtimeOS: null,
   inMailApp: false,
 
   _windowsHidden: false,
   _handledDOMWindows: [],
 
+  init: function() {            // creates icon
+    this.appName = Services.appinfo.name.toLowerCase();
+    this.FILENAME_DEFAULT = firetray.Utils.chromeToPath(
+      "chrome://firetray/skin/" +  this.appName + this.FILENAME_SUFFIX);
+    this.FILENAME_BLANK = firetray.Utils.chromeToPath(
+      "chrome://firetray/skin/blank-icon.png");
+    this.FILENAME_NEWMAIL = firetray.Utils.chromeToPath(
+      "chrome/skin/message-mail-new.png");
+
+    // init all handled windows
+    this._updateHandledDOMWindows();
+
+    // OS/platform checks
+    this.runtimeOS = Services.appinfo.OS; // "WINNT", "Linux", "Darwin"
+    // version checked during install, so we shouldn't need to care
+    let xulVer = Services.appinfo.platformVersion; // Services.vc.compare(xulVer,"2.0a")>=0
+    LOG("OS=" + this.runtimeOS + ", XULrunner=" + xulVer);
+    switch (this.runtimeOS) {
+    case "Linux":
+      Cu.import("resource://firetray/FiretrayIconLinux.jsm");
+      LOG('FiretrayIconLinux imported');
+
+      // instanciate tray icon
+      firetray.IconLinux.init();
+      LOG('IconLinux initialized');
+
+      break;
+    default:
+      ERROR("FIRETRAY: only Linux platform supported at this time. Firetray not loaded");
+      return false;
+    }
+
+    // check if in mail app
+    var mozAppId = Services.appinfo.ID;
+    if (mozAppId === THUNDERBIRD_ID || mozAppId === SEAMONKEY_ID) {
+      this.inMailApp = true;
+      try {
+        Cu.import("resource://firetray/FiretrayMessaging.jsm");
+        let prefMailNotification = firetray.Utils.prefService.getIntPref("mail_notification");
+        if (prefMailNotification !== NOTIFICATION_DISABLED)
+          firetray.Messaging.enable();
+      } catch (x) {
+        ERROR(x);
+        return false;
+      }
+    }
+    LOG('inMailApp: '+this.inMailApp);
+
+    this.initialized = true;
+    return true;
+  },
+
+  shutdown: function() {
+    if (this.inMailApp)
+      firetray.Messaging.disable();
+
+    switch (this.runtimeOS) {
+    case "Linux":
+      firetray.IconLinux.shutdown();
+      break;
+    default:
+      ERROR("runtimeOS unknown or undefined.");
+      return false;
+    }
+
+    return true;
+  },
+
+  // these get overridden in OS-specific Icon handlers
+  setImage: function(filename) {},
+  setImageDefault: function() {},
+  setText: function(text, color) {},
+  setTooltip: function(localizedMessage) {},
+  setTooltipDefault: function() {},
+
   _getBaseOrXULWindowFromDOMWindow: function(win, winType) {
     let winInterface, winOut;
     try {                       // thx Neil Deakin !!
@@ -147,54 +228,6 @@ firetray.Handler = {
       ERROR(x);
       return;
     }
-  },
-
-  init: function() {            // creates icon
-
-    // platform checks
-    let runtimeOS = Services.appinfo.OS; // "WINNT", "Linux", "Darwin"
-    // version checked during install, so we shouldn't need to care
-    let xulVer = Services.appinfo.platformVersion; // Services.vc.compare(xulVer,"2.0a")>=0
-    LOG("OS=" + runtimeOS + ", XULrunner=" + xulVer);
-    if (runtimeOS != "Linux") {
-      ERROR("FIRETRAY: only Linux platform supported at this time. Firetray not loaded");
-      return false;
-    }
-    Cu.import("resource://firetray/FiretrayIconLinux.jsm");
-    LOG('FiretrayIconLinux imported');
-
-    // init all handled windows
-    this._updateHandledDOMWindows();
-
-    // instanciate tray icon
-    firetray.IconLinux.init();
-    LOG('IconLinux initialized');
-
-    // check if in mail app
-    var mozAppId = Services.appinfo.ID;
-    if (mozAppId === THUNDERBIRD_ID || mozAppId === SEAMONKEY_ID) {
-      this.inMailApp = true;
-      try {
-        Cu.import("resource://firetray/FiretrayMessaging.jsm");
-        let prefMailNotification = firetray.Utils.prefService.getIntPref("mail_notification");
-        if (prefMailNotification !== NOTIFICATION_DISABLED)
-          firetray.Messaging.enable();
-      } catch (x) {
-        ERROR(x);
-        return false;
-      }
-    }
-    LOG('inMailApp: '+this.inMailApp);
-
-    this.initialized = true;
-    return true;
-  },
-
-  shutdown: function() {        // NOT USED YET
-    if (this.inMailApp)
-      firetray.Messaging.disable();
-
-    firetray.IconLinux.shutdown();
   }
 
 }; // firetray.Handler
diff --git a/src/modules/FiretrayIconLinux.jsm b/src/modules/FiretrayIconLinux.jsm
index 3f0581b..38c77a3 100644
--- a/src/modules/FiretrayIconLinux.jsm
+++ b/src/modules/FiretrayIconLinux.jsm
@@ -47,31 +47,22 @@ var _find_data_t = ctypes.StructType("_find_data_t", [
 firetray.IconLinux = {
   tryIcon: null,
   menu: null,
-  appName: null,
-  FILENAME_DEFAULT: null,
-  FILENAME_SUFFIX: "32.png",
-  FILENAME_NEWMAIL: "newmail.png",
   MIN_FONT_SIZE: 4,
 
   init: function() {
     try {
       // init tray icon, some variables
       this.trayIcon  = gtk.gtk_status_icon_new();
-      this.appName = Services.appinfo.name.toLowerCase();
-      this.FILENAME_DEFAULT = firetray.Utils.chromeToPath(
-        "chrome://firetray/skin/" +  this.appName + this.FILENAME_SUFFIX);
-      this.FILENAME_NEWMAIL = firetray.Utils.chromeToPath(
-        "chrome://firetray/skin/newmail.png");
     } catch (x) {
       ERROR(x);
       return false;
     }
 
-    this.setImageDefault();
+    firetray.Handler.setImageDefault();
 
     this._buildPopupMenu();
 
-    this.setTooltipDefault();
+    firetray.Handler.setTooltipDefault();
 
     // attach popupMenu to trayIcon
     try {
@@ -144,154 +135,6 @@ firetray.IconLinux = {
 
   },
 
-  setImage: function(filename) {
-    if (!this.trayIcon)
-      return false;
-    LOG(filename);
-
-    try {
-      gtk.gtk_status_icon_set_from_file(this.trayIcon,
-                                        filename);
-    } catch (x) {
-      ERROR(x);
-      return false;
-    }
-    return true;
-  },
-
-  setImageDefault: function() {
-    if (!this.FILENAME_DEFAULT)
-      throw "Default application icon filename not set";
-    this.setImage(this.FILENAME_DEFAULT);
-  },
-
-  // GTK bug: Gdk-CRITICAL **: IA__gdk_window_get_root_coords: assertion `GDK_IS_WINDOW (window)' failed
-  setTooltip: function(toolTipStr) {
-    if (!this.trayIcon)
-      return false;
-
-    try {
-      gtk.gtk_status_icon_set_tooltip_text(this.trayIcon,
-                                           toolTipStr);
-    } catch (x) {
-      ERROR(x);
-      return false;
-    }
-    return true;
-  },
-
-  setTooltipDefault: function() {
-    if (!this.appName)
-      throw "application name not initialized";
-    this.setTooltip(this.appName);
-  },
-
-  setText: function(text, color) { // TODO: split into smaller functions;
-    LOG("setText");
-    if (typeof(text) != "string")
-      throw new TypeError();
-
-    try {
-      // build background from image
-      let specialIcon = gdk.gdk_pixbuf_new_from_file(this.FILENAME_NEWMAIL, null); // GError **error);
-      let dest = gdk.gdk_pixbuf_copy(specialIcon);
-      let w = gdk.gdk_pixbuf_get_width(specialIcon);
-      let h = gdk.gdk_pixbuf_get_height(specialIcon);
-
-      // prepare colors/alpha
-      let colorMap = gdk.gdk_screen_get_system_colormap(gdk.gdk_screen_get_default());
-      let visual = gdk.gdk_colormap_get_visual(colorMap);
-      let visualDepth = visual.contents.depth;
-      LOG("colorMap="+colorMap+" visual="+visual+" visualDepth="+visualDepth);
-      let fore = new gdk.GdkColor;
-      fore.pixel = fore.red = fore.green = fore.blue = 0;
-      let alpha  = new gdk.GdkColor;
-      alpha.pixel = alpha.red = alpha.green = alpha.blue = 0xFFFF;
-      if (!fore || !alpha)
-        WARN("Undefined GdkColor fore or alpha");
-      gdk.gdk_color_parse(color, fore.address());
-      if(fore.red == alpha.red && fore.green == alpha.green && fore.blue == alpha.blue) {
-        alpha.red=0; // make sure alpha is different from fore
-      }
-      gdk.gdk_colormap_alloc_color(colorMap, fore.address(), true, true);
-      gdk.gdk_colormap_alloc_color(colorMap, alpha.address(), true, true);
-
-      // build pixmap with rectangle
-      let pm = gdk.gdk_pixmap_new(null, w, h, visualDepth);
-      let pmDrawable = ctypes.cast(pm, gdk.GdkDrawable.ptr);
-      let cr = gdk.gdk_cairo_create(pmDrawable);
-      gdk.gdk_cairo_set_source_color(cr, alpha.address());
-      cairo.cairo_rectangle(cr, 0, 0, w, h);
-      cairo.cairo_set_source_rgb(cr, 1, 1, 1);
-      cairo.cairo_fill(cr);
-
-      // build text
-      let scratch = gtk.gtk_window_new(gtk.GTK_WINDOW_TOPLEVEL);
-      let layout = gtk.gtk_widget_create_pango_layout(scratch, null);
-      gtk.gtk_widget_destroy(scratch);
-      let fnt = pango.pango_font_description_from_string("Sans 18");
-      pango.pango_font_description_set_weight(fnt,pango.PANGO_WEIGHT_SEMIBOLD);
-      pango.pango_layout_set_spacing(layout,0);
-      pango.pango_layout_set_font_description(layout, fnt);
-      LOG("layout="+layout);
-      LOG("text="+text);
-      pango.pango_layout_set_text(layout, text,-1);
-      let tw = new ctypes.int;
-      let th = new ctypes.int;
-      let sz;
-      let border = 4;
-      pango.pango_layout_get_pixel_size(layout, tw.address(), th.address());
-      LOG("tw="+tw.value+" th="+th.value);
-      // fit text to the icon by decreasing font size
-      while ( tw.value > (w - border) || th.value > (h - border) ) {
-        sz = pango.pango_font_description_get_size(fnt);
-        if(sz < this.MIN_FONT_SIZE) {
-          sz = this.MIN_FONT_SIZE;
-          break;
-        }
-        sz -= pango.PANGO_SCALE;
-        pango.pango_font_description_set_size(fnt,sz);
-        pango.pango_layout_set_font_description(layout, fnt);
-        pango.pango_layout_get_pixel_size(layout, tw.address(), th.address());
-      }
-      LOG("tw="+tw.value+" th="+th.value);
-      pango.pango_font_description_free(fnt);
-      // center text
-      let px = (w-tw.value)/2;
-      let py = (h-th.value)/2;
-
-      // draw text on pixmap
-      gdk.gdk_cairo_set_source_color(cr, fore.address());
-      cairo.cairo_move_to(cr, px, py);
-      pangocairo.pango_cairo_show_layout(cr, layout);
-      cairo.cairo_destroy(cr);
-      gobject.g_object_unref(layout);
-
-      let buf = gdk.gdk_pixbuf_get_from_drawable(null, pmDrawable, null, 0, 0, 0, 0, w, h);
-      gobject.g_object_unref(pm);
-      LOG("alpha="+alpha);
-      let alphaRed = gobject.guint16(alpha.red);
-      let alphaRed_guchar = ctypes.cast(alphaRed, gobject.guchar);
-      let alphaGreen = gobject.guint16(alpha.green);
-      let alphaGreen_guchar = ctypes.cast(alphaGreen, gobject.guchar);
-      let alphaBlue = gobject.guint16(alpha.blue);
-      let alphaBlue_guchar = ctypes.cast(alphaBlue, gobject.guchar);
-      let bufAlpha = gdk.gdk_pixbuf_add_alpha(buf, true, alphaRed_guchar, alphaGreen_guchar, alphaBlue_guchar);
-      gobject.g_object_unref(buf);
-
-      // merge the rendered text on top
-      gdk.gdk_pixbuf_composite(bufAlpha,dest,0,0,w,h,0,0,1,1,gdk.GDK_INTERP_NEAREST,255);
-      gobject.g_object_unref(bufAlpha);
-
-      gtk.gtk_status_icon_set_from_pixbuf(this.trayIcon, dest);
-    } catch (x) {
-      ERROR(x);
-      return false;
-    }
-
-    return true;
-  },
-
   /**
    * Iterate over all Gtk toplevel windows to find a window. We rely on
    * Service.wm to watch windows correctly: we should find only one window.
@@ -394,3 +237,152 @@ firetray.IconLinux = {
   }
 
 }; // firetray.IconLinux
+
+
+firetray.Handler.setImage = function(filename) {
+  if (!firetray.IconLinux.trayIcon)
+    return false;
+  LOG(filename);
+
+  try {
+    gtk.gtk_status_icon_set_from_file(firetray.IconLinux.trayIcon,
+                                      filename);
+  } catch (x) {
+    ERROR(x);
+    return false;
+  }
+  return true;
+};
+
+firetray.Handler.setImageDefault = function() {
+  if (!this.FILENAME_DEFAULT)
+    throw "Default application icon filename not set";
+  this.setImage(this.FILENAME_DEFAULT);
+};
+
+// GTK bug: Gdk-CRITICAL **: IA__gdk_window_get_root_coords: assertion `GDK_IS_WINDOW (window)' failed
+firetray.Handler.setTooltip = function(toolTipStr) {
+  if (!firetray.IconLinux.trayIcon)
+    return false;
+
+  try {
+    gtk.gtk_status_icon_set_tooltip_text(firetray.IconLinux.trayIcon,
+                                         toolTipStr);
+  } catch (x) {
+    ERROR(x);
+    return false;
+  }
+  return true;
+};
+
+firetray.Handler.setTooltipDefault = function() {
+  if (!this.appName)
+    throw "application name not initialized";
+  this.setTooltip(this.appName);
+};
+
+firetray.Handler.setText = function(text, color) { // TODO: split into smaller functions;
+  LOG("setText");
+  if (typeof(text) != "string")
+    throw new TypeError();
+
+  try {
+    // build background from image
+    let specialIcon = gdk.gdk_pixbuf_new_from_file(this.FILENAME_BLANK, null); // GError **error);
+    let dest = gdk.gdk_pixbuf_copy(specialIcon);
+    let w = gdk.gdk_pixbuf_get_width(specialIcon);
+    let h = gdk.gdk_pixbuf_get_height(specialIcon);
+
+    // prepare colors/alpha
+    let colorMap = gdk.gdk_screen_get_system_colormap(gdk.gdk_screen_get_default());
+    let visual = gdk.gdk_colormap_get_visual(colorMap);
+    let visualDepth = visual.contents.depth;
+    LOG("colorMap="+colorMap+" visual="+visual+" visualDepth="+visualDepth);
+    let fore = new gdk.GdkColor;
+    fore.pixel = fore.red = fore.green = fore.blue = 0;
+    let alpha  = new gdk.GdkColor;
+    alpha.pixel = alpha.red = alpha.green = alpha.blue = 0xFFFF;
+    if (!fore || !alpha)
+      WARN("Undefined GdkColor fore or alpha");
+    gdk.gdk_color_parse(color, fore.address());
+    if(fore.red == alpha.red && fore.green == alpha.green && fore.blue == alpha.blue) {
+      alpha.red=0; // make sure alpha is different from fore
+    }
+    gdk.gdk_colormap_alloc_color(colorMap, fore.address(), true, true);
+    gdk.gdk_colormap_alloc_color(colorMap, alpha.address(), true, true);
+
+    // build pixmap with rectangle
+    let pm = gdk.gdk_pixmap_new(null, w, h, visualDepth);
+    let pmDrawable = ctypes.cast(pm, gdk.GdkDrawable.ptr);
+    let cr = gdk.gdk_cairo_create(pmDrawable);
+    gdk.gdk_cairo_set_source_color(cr, alpha.address());
+    cairo.cairo_rectangle(cr, 0, 0, w, h);
+    cairo.cairo_set_source_rgb(cr, 1, 1, 1);
+    cairo.cairo_fill(cr);
+
+    // build text
+    let scratch = gtk.gtk_window_new(gtk.GTK_WINDOW_TOPLEVEL);
+    let layout = gtk.gtk_widget_create_pango_layout(scratch, null);
+    gtk.gtk_widget_destroy(scratch);
+    let fnt = pango.pango_font_description_from_string("Sans 18");
+    pango.pango_font_description_set_weight(fnt,pango.PANGO_WEIGHT_SEMIBOLD);
+    pango.pango_layout_set_spacing(layout,0);
+    pango.pango_layout_set_font_description(layout, fnt);
+    LOG("layout="+layout);
+    LOG("text="+text);
+    pango.pango_layout_set_text(layout, text,-1);
+    let tw = new ctypes.int;
+    let th = new ctypes.int;
+    let sz;
+    let border = 4;
+    pango.pango_layout_get_pixel_size(layout, tw.address(), th.address());
+    LOG("tw="+tw.value+" th="+th.value);
+    // fit text to the icon by decreasing font size
+    while ( tw.value > (w - border) || th.value > (h - border) ) {
+      sz = pango.pango_font_description_get_size(fnt);
+      if(sz < firetray.IconLinux.MIN_FONT_SIZE) {
+        sz = firetray.IconLinux.MIN_FONT_SIZE;
+        break;
+      }
+      sz -= pango.PANGO_SCALE;
+      pango.pango_font_description_set_size(fnt,sz);
+      pango.pango_layout_set_font_description(layout, fnt);
+      pango.pango_layout_get_pixel_size(layout, tw.address(), th.address());
+    }
+    LOG("tw="+tw.value+" th="+th.value);
+    pango.pango_font_description_free(fnt);
+    // center text
+    let px = (w-tw.value)/2;
+    let py = (h-th.value)/2;
+
+    // draw text on pixmap
+    gdk.gdk_cairo_set_source_color(cr, fore.address());
+    cairo.cairo_move_to(cr, px, py);
+    pangocairo.pango_cairo_show_layout(cr, layout);
+    cairo.cairo_destroy(cr);
+    gobject.g_object_unref(layout);
+
+    let buf = gdk.gdk_pixbuf_get_from_drawable(null, pmDrawable, null, 0, 0, 0, 0, w, h);
+    gobject.g_object_unref(pm);
+    LOG("alpha="+alpha);
+    let alphaRed = gobject.guint16(alpha.red);
+    let alphaRed_guchar = ctypes.cast(alphaRed, gobject.guchar);
+    let alphaGreen = gobject.guint16(alpha.green);
+    let alphaGreen_guchar = ctypes.cast(alphaGreen, gobject.guchar);
+    let alphaBlue = gobject.guint16(alpha.blue);
+    let alphaBlue_guchar = ctypes.cast(alphaBlue, gobject.guchar);
+    let bufAlpha = gdk.gdk_pixbuf_add_alpha(buf, true, alphaRed_guchar, alphaGreen_guchar, alphaBlue_guchar);
+    gobject.g_object_unref(buf);
+
+    // merge the rendered text on top
+    gdk.gdk_pixbuf_composite(bufAlpha,dest,0,0,w,h,0,0,1,1,gdk.GDK_INTERP_NEAREST,255);
+    gobject.g_object_unref(bufAlpha);
+
+    gtk.gtk_status_icon_set_from_pixbuf(firetray.IconLinux.trayIcon, dest);
+  } catch (x) {
+    ERROR(x);
+    return false;
+  }
+
+  return true;
+};
diff --git a/src/modules/FiretrayMessaging.jsm b/src/modules/FiretrayMessaging.jsm
index 0881734..5c1037b 100644
--- a/src/modules/FiretrayMessaging.jsm
+++ b/src/modules/FiretrayMessaging.jsm
@@ -8,7 +8,7 @@ const Cu = Components.utils;
 
 Cu.import("resource:///modules/mailServices.js");
 Cu.import("resource://gre/modules/PluralForm.jsm");
-Cu.import("resource://firetray/FiretrayIconLinux.jsm");
+// Cu.import("resource://firetray/FiretrayHandler.jsm");
 Cu.import("resource://firetray/commons.js");
 
 const FLDR_UNINTERESTING =
@@ -52,8 +52,8 @@ firetray.Messaging = {
     if (!this.enabled)
       return;
 
-    MailServices.mailSession.RemoveFolderListener(this);
-    firetray.IconLinux.setImageDefault();
+    MailServices.mailSession.RemoveFolderListener(this.mailSessionListener);
+    firetray.Handler.setImageDefault();
 
     this.enabled = false;
   },
@@ -110,16 +110,16 @@ firetray.Messaging = {
 
     // update icon
     if (this._unreadMsgCount == 0) {
-      firetray.IconLinux.setImageDefault();
-      firetray.IconLinux.setTooltipDefault();
+      firetray.Handler.setImageDefault();
+      firetray.Handler.setTooltipDefault();
     } else if (this._unreadMsgCount > 0) {
       let prefIconTextColor = firetray.Utils.prefService.getCharPref("icon_text_color");
-      firetray.IconLinux.setText(this._unreadMsgCount.toString(), prefIconTextColor);
+      firetray.Handler.setText(this._unreadMsgCount.toString(), prefIconTextColor);
       let localizedMessage = PluralForm.get(
         this._unreadMsgCount,
         firetray.Utils.strings.GetStringFromName("tooltip.unread_messages"))
         .replace("#1", this._unreadMsgCount);;
-      firetray.IconLinux.setTooltip(localizedMessage);
+      firetray.Handler.setTooltip(localizedMessage);
     } else {
       throw "negative message count"; // should never happen
     }