diff --git a/fields/group.py b/fields/group.py
index 1bc235b..97d6cb7 100644
--- a/fields/group.py
+++ b/fields/group.py
@@ -289,32 +289,25 @@ class UiGroup:
       </x>
      </x>''')
 
-    # PX that renders a group of searches.
+    # PX that renders a group of searches
     pxViewSearches = Px('''
-     <x var="expanded=req.get(field.labelId, 'collapsed') == 'expanded'">
+     <x var="collapse=field.getCollapseInfo(field.labelId, req)">
       <!-- Group name, prefixed by the expand/collapse icon -->
-      <div class="portletGroup">
-       <img class="clickable" style="margin-right: 3px" align=":dleft"
-            id=":'%s_img' % field.labelId"
-            src=":expanded and url('collapse.gif') or url('expand.gif')"
-            onclick=":'toggleCookie(%s)' % q(field.labelId)"/>
+      <div class="portletGroup"><x>:collapse.px</x>
        <x if="not field.translated">:_(field.labelId)</x>
        <x if="field.translated">:field.translated</x>
       </div>
       <!-- Group content -->
-      <div var="display=expanded and 'display:block' or 'display:none'"
-           id=":field.labelId" style=":'padding-left: 10px; %s' % display">
+      <div id=":collapse.id" style=":'padding-left: 10px; %s' % collapse.style">
        <x for="searches in field.elements">
         <x for="elem in searches">
          <!-- An inner group within this group -->
-         <x if="elem.type == 'group'"
-            var2="field=elem">:field.pxViewSearches</x>
+         <x if="elem.type== 'group'" var2="field=elem">:field.pxViewSearches</x>
          <!-- A search -->
-         <x if="elem.type != 'group'" var2="search=elem">:search.pxView</x>
+         <x if="elem.type!= 'group'" var2="search=elem">:search.pxView</x>
         </x>
        </x>
-      </div>
-     </x>''')
+      </div></x>''')
 
     # PX that renders a group of transitions.
     pxViewTransitions = Px('''
@@ -349,7 +342,7 @@ class UiGroup:
         self.group = group
         self.columnsWidths = [col.width for col in group.columns]
         self.columnsAligns = [col.align for col in group.columns]
-        # Names of i18n labels for this group.
+        # Names of i18n labels for this group
         labelName = self.name
         prefix = className
         if group.label:
@@ -397,4 +390,9 @@ class UiGroup:
                 for i in range(freeColumns): lastRow.append('')
             # Create a new row
             self.elements.append([element])
+
+    def getCollapseInfo(self, id, request):
+        '''Returns a Collapsible instance, that determines if this group,
+           represented as an expandable menu item, is collapsed or expanded.'''
+        return gutils.Collapsible(id, request)
 # ------------------------------------------------------------------------------
diff --git a/fields/ref.py b/fields/ref.py
index 289a626..5ff6989 100644
--- a/fields/ref.py
+++ b/fields/ref.py
@@ -226,15 +226,10 @@ class Ref(Field):
       </div>
      </div>''')
 
-    pxToggleIcon = Px('''
-     <img class="clickable" onclick="toggleCookie('appyHistory')"
-          src=":True and url('collapse.gif') or url('expand.gif')"
-          align=":dleft" id="appyHistory_img" style="padding-right:4px"/>''')
-
     # PX that displays referred objects as a list
     pxViewList = Px('''
      <div if="not innerRef or mayAdd or mayLink" style="margin-bottom: 4px">
-      <x if="field.collapsible">:field.pxToggleIcon</x>
+      <x if="field.collapsible and objects">:collapse.px</x>
       <span if="subLabel" class="discreet">:_(subLabel)</span>
       (<span class="discreet">:totalNumber</span>) 
       <x>:field.pxAdd</x>
@@ -258,7 +253,8 @@ class Ref(Field):
         if="not objects and (innerRef and mayAdd)">:_('no_ref')</p>
 
      <!-- Linked objects -->
-     <table if="objects" class=":not innerRef and 'list' or ''"
+     <table if="objects" id=":collapse.id" style=":collapse.style"
+            class=":not innerRef and 'list' or ''"
             width=":innerRef and '100%' or field.layouts['view'].width"
             var2="columns=ztool.getColumnsSpecifiers(tiedClassName, \
                    field.getAttribute(obj, 'shownInfo'), dir)">
@@ -350,6 +346,7 @@ class Ref(Field):
                         (totalNumber &gt; 1);
              showSubTitles=showSubTitles|\
                            req.get('showSubTitles', 'true') == 'true';
+             collapse=field.getCollapseInfo(obj, True);
              subLabel='selectable_objects'">:field.pxViewList</x>''')
 
     # PX that displays referred objects as dropdown menus.
@@ -450,6 +447,7 @@ class Ref(Field):
              checkboxesEnabled=field.getAttribute(zobj, 'checkboxes') and \
                                (layoutType != 'cell');
              checkboxes=checkboxesEnabled and (totalNumber &gt; 1);
+             collapse=field.getCollapseInfo(obj, False);
              showSubTitles=req.get('showSubTitles', 'true') == 'true'">
       <!-- JS tables storing checkbox statuses if checkboxes are enabled -->
       <script if="checkboxesEnabled and renderAll and (render == 'list')"
@@ -1495,6 +1493,16 @@ class Ref(Field):
         tiedUrl = tied.getUrl(nav=self.getNavInfo(obj, number+1, len(uids)))
         return obj.goto(tiedUrl)
 
+    def getCollapseInfo(self, obj, inPickList):
+        '''Returns a Collapsible instance, that determines if the "tied objects"
+           or "available objects" zone (depending on p_inPickList) is collapsed
+           or expanded.'''
+        # Create the ID of the collapsible zone.
+        suffix = inPickList and 'poss' or 'objs'
+        id = '%s_%s_%s' % (obj.klass.__name__, self.name, suffix)
+        return gutils.Collapsible(id, obj.request, default='expanded',
+                                  display='table')
+
 def autoref(klass, field):
     '''klass.field is a Ref to p_klass. This kind of auto-reference can't be
        declared in the "normal" way, like this:
diff --git a/gen/mixins/__init__.py b/gen/mixins/__init__.py
index bca4fb3..9d69739 100644
--- a/gen/mixins/__init__.py
+++ b/gen/mixins/__init__.py
@@ -1240,6 +1240,11 @@ class BaseMixin:
             res.append(event)
         return Object(events=res, totalNumber=len(history))
 
+    def getHistoryCollapse(self):
+        '''Gets a Collapsible instance for showing a collapse or expanded
+           history in this object.'''
+        return Collapsible('appyHistory', self.REQUEST)
+
     def mayNavigate(self):
         '''May the currently logged user see the navigation panel linked to
            this object?'''
diff --git a/gen/ui/appy.js b/gen/ui/appy.js
index 6191080..f106043 100644
--- a/gen/ui/appy.js
+++ b/gen/ui/appy.js
@@ -673,13 +673,13 @@ function readCookie(name) {
   return null;
 }
 
-function toggleCookie(cookieId) {
+function toggleCookie(cookieId, display, defaultValue) {
   // What is the state of this boolean (expanded/collapsed) cookie?
   var state = readCookie(cookieId);
   if ((state != 'collapsed') && (state != 'expanded')) {
-    // No cookie yet, create it.
-    createCookie(cookieId, 'collapsed');
-    state = 'collapsed';
+    // No cookie yet, create it
+    createCookie(cookieId, defaultValue);
+    state = defaultValue;
   }
   var hook = document.getElementById(cookieId); // The hook is the part of
   // the HTML document that needs to be shown or hidden.
@@ -688,7 +688,7 @@ function toggleCookie(cookieId) {
   var imgSrc = 'ui/expand.gif';
   if (state == 'collapsed') {
     // Show the HTML zone
-    displayValue = 'block';
+    displayValue = display;
     imgSrc = 'ui/collapse.gif';
     newState = 'expanded';
   }
diff --git a/gen/utils.py b/gen/utils.py
index 0cfe15d..fdaf8a1 100644
--- a/gen/utils.py
+++ b/gen/utils.py
@@ -1,5 +1,6 @@
 # ------------------------------------------------------------------------------
 import re, os, os.path, base64, urllib
+from appy.px import Px
 from appy.shared import utils as sutils
 
 # Function for creating a Zope object ------------------------------------------
@@ -251,5 +252,29 @@ class Tool(Model):
     '''Subclass me to extend or modify the Tool class.'''
 class User(Model):
     '''Subclass me to extend or modify the User class.'''
-# ------------------------------------------------------------------------------
 
+# ------------------------------------------------------------------------------
+class Collapsible:
+    '''Represents a chunk of HTML code that can be collapsed/expanded via a
+       plus/minus icon.'''
+
+    # Plus/minus icon allowing to collapse/expand a chunk of HTML
+    px = Px('''
+     <img id=":'%s_img' % collapse.id" class="clickable" align=":dleft"
+          onclick=":'toggleCookie(%s,%s,%s)' % \
+                   (q(collapse.id), q(collapse.display), q(collapse.default))"
+          src=":collapse.expanded and url('collapse.gif') or url('expand.gif')"
+          style="padding-right:4px"/>''')
+
+    def __init__(self, id, request, default='collapsed', display='block'):
+        '''p_display is the value of style attribute "display" for the XHTML
+           element when it must be displayed. By default it is "block"; for a
+           table it must be "table", etc.'''
+        self.id = id # The ID of the collapsible HTML element
+        self.request = request # The request object
+        self.default = default
+        self.display = display
+        # Must the element be collapsed or expanded ?
+        self.expanded = request.get(id, default) == 'expanded'
+        self.style = 'display:%s' % (self.expanded and self.display or 'none')
+# ------------------------------------------------------------------------------
diff --git a/gen/wrappers/__init__.py b/gen/wrappers/__init__.py
index b927265..9b4e95b 100644
--- a/gen/wrappers/__init__.py
+++ b/gen/wrappers/__init__.py
@@ -397,16 +397,13 @@ class AbstractWrapper(object):
      <div if="not zobj.isTemporary()"
           var2="hasHistory=zobj.hasHistory();
                 historyMaxPerPage=req.get('maxPerPage', 5);
-                historyExpanded=req.get('appyHistory','collapsed')=='expanded';
+                collapse=zobj.getHistoryCollapse();
                 creator=zobj.Creator()">
       <table width="100%" class="summary" cellpadding="0" cellspacing="0">
        <tr>
         <td colspan="2" class="by">
          <!-- Plus/minus icon for accessing history -->
-         <x if="hasHistory">
-          <img class="clickable" onclick="toggleCookie('appyHistory')"
-             src=":historyExpanded and url('collapse.gif') or url('expand.gif')"
-             align=":dleft" id="appyHistory_img" style="padding-right:4px"/>
+         <x if="hasHistory"><x>:collapse.px</x>
           <x>:_('object_history')</x> &mdash;
          </x>
 
@@ -434,8 +431,7 @@ class AbstractWrapper(object):
        <!-- Object history -->
        <tr if="hasHistory">
         <td colspan="2">
-         <span id="appyHistory"
-               style=":historyExpanded and 'display:block' or 'display:none'">
+         <span id=":collapse.id" style=":collapse.style">
           <div var="ajaxHookId=zobj.id + '_history'" id=":ajaxHookId">
            <script type="text/javascript">::'askObjectHistory(%s,%s,%d,0)' % \
              (q(ajaxHookId), q(zobj.absolute_url()), \