diff --git a/src/chrome/content/options.js b/src/chrome/content/options.js
index 008be0a..8e06ee3 100644
--- a/src/chrome/content/options.js
+++ b/src/chrome/content/options.js
@@ -1,5 +1,13 @@
 /* -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 
+/* FIXME: instantApply pref defaults to false on Windows. But the Firetray pref
+window was originaly crafted for instantApply platforms: some UI changes do
+also change prefs programmaticaly. For a consistant behaviour across all
+instantApply cases, we should probably not set prefs dynamically, that is leave
+it all to the UI. See:
+http://forums.mozillazine.org/viewtopic.php?f=19&t=2743643
+https://groups.google.com/forum/#!topic/mozilla.dev.extensions/SBGIogdIiwE */
+
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cu = Components.utils;
@@ -15,7 +23,6 @@ const TREELEVEL_EXCLUDED_ACCOUNTS = 1;
 
 const PREF_DEFAULT_PANE = "pref-pane-windows";
 
-
 let log = firetray.Logging.getLogger("firetray.UIOptions");
 
 var firetrayUIOptions = {
@@ -23,6 +30,7 @@ var firetrayUIOptions = {
   prefwindow: null,
 
   onLoad: function(e) {
+    log.debug("FULL FEATURED="+firetray.Handler.support['full_feat']);
     this.strings = document.getElementById("firetray-options-strings");
     this.prefwindow = document.getElementById("firetray-preferences");
     if (!this.prefwindow)
@@ -40,15 +48,20 @@ var firetrayUIOptions = {
         FIRETRAY_CHAT_SUPPORTED_OS.indexOf(firetray.Handler.runtimeOS) > -1) {
       Cu.import("resource://firetray/"+firetray.Handler.runtimeOS+"/FiretrayChat.jsm");
       this.initChatControls();
-    } else
-    this.hidePrefPane("pref-pane-chat");
+    } else {
+      this.hidePrefPane("pref-pane-chat");
+    };
 
     this.updateWindowAndIconOptions();
     this.updateScrollOptions();
     this.initAppIconType();
-    this.initAppIconNames();
-    if (firetray.Handler.inMailApp)
-      this.initNewMailIconNames();
+    if (firetray.Handler.support['full_feat']) {
+      this.initAppIconNames();
+      if (firetray.Handler.inMailApp)
+        this.initNewMailIconNames();
+    } else {
+      this.hideUnsupportedOptions();
+    };
 
     window.sizeToContent();
   },
@@ -74,6 +87,28 @@ var firetrayUIOptions = {
     }
   },
 
+  hideUnsupportedOptions: function() { // full_feat
+    // windows prefs
+    ['ui_hides_last_only', 'ui_start_hidden', 'ui_show_activates',
+     'ui_remember_desktop'].forEach(function(id){
+       document.getElementById(id).hidden = true;
+     });
+
+    // icon prefs
+    ['app_icon_default', 'ui_show_icon_on_hide', 'ui_scroll_hides',
+     'ui_radiogroup_scroll'].forEach(function(id){
+       document.getElementById(id).hidden = true;
+     });
+    document.getElementById("ui_scroll_hides").setAttribute("oncommand", void(0));
+
+    // mail prefs
+    document.getElementById("newmail_icon_names").hidden = true;
+    for (let i=1; i<4; ++i) {
+      document.getElementById("radio_mail_notification_newmail_icon_name"+i).
+        setAttribute("observes", void(0));
+    }
+  },
+
   hidePrefPane: function(name){
     let radio = document.getAnonymousElementByAttribute(this.prefwindow, "pane", name);
     if (radio.selected)
@@ -81,8 +116,10 @@ var firetrayUIOptions = {
     radio.hidden = true;
   },
 
-  hideElement: function(targetNode, hiddenval) {
-    targetNode.hidden = hiddenval;
+  hideChildren: function(group, hiddenval) {
+    let children = group.childNodes;
+    for (let i=0, len=children.length; i<len ; ++i)
+      children[i].hidden = hiddenval;
   },
 
   disableChildren: function(group, disableval) {
@@ -120,8 +157,9 @@ var firetrayUIOptions = {
   },
 
   updateScrollOptions: function() {
-    let scroll_hides = document.getElementById("ui_scroll_hides").checked;
-    this.disableChildren(document.getElementById("ui_radiogroup_scroll"), !scroll_hides);
+    let ui_scroll_hides = document.getElementById("ui_scroll_hides");
+    this.disableChildren(document.getElementById("ui_radiogroup_scroll"),
+                         !ui_scroll_hides.checked);
   },
 
   initAppIconType: function() {
@@ -179,13 +217,15 @@ var firetrayUIOptions = {
   },
 
   disableIconTypeMaybe: function(appIconType) {
+    if (firetray.Handler.support['full_feat']) {
+      let appIconDefaultGroup = document.getElementById("app_icon_default");
+      this.disableNChildren(appIconDefaultGroup, 2,
+        (appIconType !== FIRETRAY_APPLICATION_ICON_TYPE_THEMED));
+    }
+
     let appIconCustomGroup = document.getElementById("app_icon_custom");
     this.disableChildren(appIconCustomGroup,
       (appIconType !== FIRETRAY_APPLICATION_ICON_TYPE_CUSTOM));
-
-    let appIconDefaultGroup = document.getElementById("app_icon_default");
-    this.disableNChildren(appIconDefaultGroup, 2,
-      (appIconType !== FIRETRAY_APPLICATION_ICON_TYPE_THEMED));
   },
 
   initMailControls: function() {
@@ -289,9 +329,11 @@ var firetrayUIOptions = {
     this.disableChildren(iconTextColor,
       (notificationSetting !== FIRETRAY_NOTIFICATION_MESSAGE_COUNT));
 
-    let newMailIconNames = document.getElementById("newmail_icon_names");
-    this.disableNChildren(newMailIconNames, 2,
-      (notificationSetting !== FIRETRAY_NOTIFICATION_NEWMAIL_ICON));
+    if (firetray.Handler.support['full_feat']) {
+      let newMailIconNames = document.getElementById("newmail_icon_names");
+      this.disableNChildren(newMailIconNames, 2,
+        (notificationSetting !== FIRETRAY_NOTIFICATION_NEWMAIL_ICON));
+    }
 
     let customIconGroup = document.getElementById("custom_mail_icon");
     this.disableChildren(customIconGroup,
@@ -309,8 +351,10 @@ var firetrayUIOptions = {
     let mailNotificationType = +radioMailNotify.getItemAtIndex(radioMailNotify.selectedIndex).value;
     if (msgCountTypeIsNewMessages && (mailNotificationType === FIRETRAY_NOTIFICATION_MESSAGE_COUNT)) {
       radioMailNotify.selectedIndex = this.radioGetIndexByValue(radioMailNotify, FIRETRAY_NOTIFICATION_NEWMAIL_ICON);
-      let newMailIconNames = document.getElementById("newmail_icon_names");
-      this.disableNChildren(newMailIconNames, 2, false);
+      if (firetray.Handler.support['full_feat']) {
+        let newMailIconNames = document.getElementById("newmail_icon_names");
+        this.disableNChildren(newMailIconNames, 2, false);
+      }
       firetray.Utils.prefService.setIntPref("mail_notification_type", FIRETRAY_NOTIFICATION_NEWMAIL_ICON);
     }
   },
diff --git a/src/chrome/content/overlay.js b/src/chrome/content/overlay.js
index ef0d805..216e569 100644
--- a/src/chrome/content/overlay.js
+++ b/src/chrome/content/overlay.js
@@ -41,6 +41,7 @@ var firetrayChrome = { // each new window gets a new firetrayChrome !
     firetray_log.debug('Firetray UNLOADED !');
   },
 
+    // BUG: CLOSE not emitted on TB (24, 27) win32 (XP, 7) ?!
   /* until we find a fix (TODO), we need to set browser.tabs.warnOnClose=false
    to prevent the popup when closing a window with multiple tabs and when
    hides_on_close is set (we are not actually closing the tabs!). There is no
diff --git a/src/modules/FiretrayHandler.jsm b/src/modules/FiretrayHandler.jsm
index 941ee5b..4fc4fa3 100644
--- a/src/modules/FiretrayHandler.jsm
+++ b/src/modules/FiretrayHandler.jsm
@@ -62,6 +62,7 @@ firetray.Handler = {
     }
     throw new Error("not resolved");
   })(),
+  support: {chat: false, full_feat: false},
 
   init: function() {            // does creates icon
     firetray.PrefListener.register(false);
@@ -79,6 +80,11 @@ firetray.Handler = {
     Cu.import("resource://firetray/"+this.runtimeOS+"/FiretrayWindow.jsm");
     log.debug("FiretrayWindow "+this.runtimeOS+" imported");
 
+    this.support['chat'] = FIRETRAY_CHAT_SUPPORTED_OS
+      .indexOf(this.runtimeOS) > -1;
+    this.support['full_feat']  = FIRETRAY_FULL_FEAT_SUPPORTED_OS
+      .indexOf(firetray.Handler.runtimeOS) > -1;
+
     if (this.appId === FIRETRAY_APP_DB['thunderbird']['id'] ||
         this.appId === FIRETRAY_APP_DB['seamonkey']['id'])
       this.inMailApp = true;
@@ -113,7 +119,7 @@ firetray.Handler = {
     let chatIsProvided = this.isChatProvided();
     log.info('isChatProvided='+chatIsProvided);
     if (chatIsProvided) {
-      if (this.isChatSupported()) {
+      if (this.support['chat']) {
         Cu.import("resource://firetray/FiretrayMessaging.jsm"); // needed for existsChatAccount
         Cu.import("resource://firetray/"+this.runtimeOS+"/FiretrayChat.jsm");
         firetray.Utils.addObservers(firetray.Handler, [
@@ -163,7 +169,7 @@ firetray.Handler = {
 
   shutdown: function() {
     log.debug("Disabling Handler");
-    if (firetray.Handler.isChatProvided() && firetray.Handler.isChatSupported()
+    if (firetray.Handler.isChatProvided() && firetray.Handler.support['chat']
         && firetray.Chat.initialized)
       firetray.Chat.shutdown();
 
@@ -192,10 +198,6 @@ firetray.Handler = {
     return this.appHasChat && Services.prefs.getBoolPref("mail.chat.enabled");
   },
 
-  isChatSupported: function() {
-    return FIRETRAY_CHAT_SUPPORTED_OS.indexOf(this.runtimeOS) > -1;
-  },
-
   tryCloseLibs: function() {
     try {
       for (let libName in this.ctypesLibs) {
@@ -575,7 +577,7 @@ firetray.MailChatPrefListener = new PrefListener(
       let enableChatCond =
             (firetray.Handler.appHasChat &&
              firetray.Utils.prefService.getBoolPref("chat_icon_enable") &&
-             firetray.Handler.isChatSupported());
+             firetray.Handler.support['chat']);
       if (!enableChatCond) return;
 
       if (Services.prefs.getBoolPref("mail.chat.enabled")) {
diff --git a/src/modules/commons.js b/src/modules/commons.js
index cd49ad8..c0f3f1f 100644
--- a/src/modules/commons.js
+++ b/src/modules/commons.js
@@ -4,8 +4,9 @@
    automatically provided by this module */
 var EXPORTED_SYMBOLS =
   [ "firetray", "FIRETRAY_VERSION", "FIRETRAY_SUPPORTED_OS",
-    "FIRETRAY_CHAT_SUPPORTED_OS", "FIRETRAY_ID", "FIRETRAY_PREF_BRANCH",
-    "FIRETRAY_SPLASH_PAGE", "FIRETRAY_APPLICATION_ICON_TYPE_THEMED",
+    "FIRETRAY_CHAT_SUPPORTED_OS", "FIRETRAY_FULL_FEAT_SUPPORTED_OS",
+    "FIRETRAY_ID", "FIRETRAY_PREF_BRANCH", "FIRETRAY_SPLASH_PAGE",
+    "FIRETRAY_APPLICATION_ICON_TYPE_THEMED",
     "FIRETRAY_APPLICATION_ICON_TYPE_CUSTOM",
     "FIRETRAY_NOTIFICATION_MESSAGE_COUNT",
     "FIRETRAY_NOTIFICATION_NEWMAIL_ICON", "FIRETRAY_NOTIFICATION_CUSTOM_ICON",
@@ -26,6 +27,7 @@ Cu.import("resource://firetray/logging.jsm");
 const FIRETRAY_VERSION           = "0.4.99"; // needed for sync call of onVersionChange() :(
 const FIRETRAY_SUPPORTED_OS      = ['linux', 'winnt']; // install.rdf sync :(
 const FIRETRAY_CHAT_SUPPORTED_OS = ['linux'];
+const FIRETRAY_FULL_FEAT_SUPPORTED_OS = FIRETRAY_CHAT_SUPPORTED_OS;
 const FIRETRAY_ID                = "{9533f794-00b4-4354-aa15-c2bbda6989f8}";
 const FIRETRAY_PREF_BRANCH       = "extensions.firetray.";
 const FIRETRAY_SPLASH_PAGE       = "http://foudfou.github.com/FireTray/";
diff --git a/src/modules/ctypes/winnt/win32.jsm b/src/modules/ctypes/winnt/win32.jsm
index dc71e30..4a0610e 100644
--- a/src/modules/ctypes/winnt/win32.jsm
+++ b/src/modules/ctypes/winnt/win32.jsm
@@ -15,6 +15,8 @@ var win32 = new function() {
     'XP':    51,    // 2001
     '2K':    50,    // 2000
   };
+  // could also parse Cc["@mozilla.org/network/protocol;1?name=http"].
+  //   getService(Ci.nsIHttpProtocolHandler).oscpu
   this.WINVER = null;                 // initialized in kernel32.jsm
 
   this.BOOL      = ctypes.bool;