Calender widget does not save time zone value

adb.xml

<plominodatabase id="adb">
  <design>
    <dbsettings version="1.16">
      <AboutDescription type="Products.Archetypes.Field.TextField"><![CDATA[]]></AboutDescription>
      <UsingDescription type="Products.Archetypes.Field.TextField"><![CDATA[]]></UsingDescription>
      <IndexAttachments type="Products.Archetypes.Field.BooleanField">False</IndexAttachments>
      <FulltextIndex type="Products.Archetypes.Field.BooleanField">True</FulltextIndex>
      <IndexInPortal type="Products.Archetypes.Field.BooleanField">False</IndexInPortal>
      <debugMode type="Products.Archetypes.Field.BooleanField">False</debugMode>
      <CountDocuments type="Products.Archetypes.Field.BooleanField">False</CountDocuments>
      <DateTimeFormat type="Products.Archetypes.Field.StringField">%Y-%m-%d</DateTimeFormat>
      <StartPage type="Products.Archetypes.Field.StringField"/>
      <i18n type="Products.Archetypes.Field.StringField"/>
      <DoNotListUsers type="Products.Archetypes.Field.BooleanField">False</DoNotListUsers>
      <DoNotReindex type="Products.Archetypes.Field.BooleanField">False</DoNotReindex>
      <excludeFromNav type="Products.Archetypes.Field.BooleanField">False</excludeFromNav>
      <acl AnomynousAccessRight="NoAccess" AuthenticatedAccessRight="NoAccess">
        <params id="UserRoles">
<param>
<value><struct>
</struct></value>
</param>
</params>
        <params id="SpecificRights">
<param>
<value><struct>
<member>
<name>specific_deletedocument</name>
<value><string>PlominoAuthor</string></value>
</member>
</struct></value>
</param>
</params>
      </acl>
    </dbsettings>
    <element id="frmDemo" title="Demo" type="PlominoForm">
      <id type="Products.Archetypes.Field.StringField">frmDemo</id>
      <onCreateDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onCreateDocument>
      <onOpenDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onOpenDocument>
      <beforeSaveDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></beforeSaveDocument>
      <onSaveDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onSaveDocument>
      <onDeleteDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></onDeleteDocument>
      <onSearch type="Products.Archetypes.Field.TextField"><![CDATA[]]></onSearch>
      <beforeCreateDocument type="Products.Archetypes.Field.TextField"><![CDATA[]]></beforeCreateDocument>
      <FormLayout type="Products.Archetypes.Field.TextField"><![CDATA[
<p>Date: <span class="plominoFieldClass">today_date</span></p>
<p>Last modified date: <span class="plominoFieldClass">title_text</span></p>
]]></FormLayout>
      <FormMethod type="Products.Archetypes.Field.TextField"><![CDATA[Auto]]></FormMethod>
      <DocumentTitle type="Products.Archetypes.Field.TextField"><![CDATA[]]></DocumentTitle>
      <DynamicDocumentTitle type="Products.Archetypes.Field.BooleanField">False</DynamicDocumentTitle>
      <StoreDynamicDocumentTitle type="Products.Archetypes.Field.BooleanField">False</StoreDynamicDocumentTitle>
      <DocumentId type="Products.Archetypes.Field.TextField"><![CDATA[]]></DocumentId>
      <ActionBarPosition type="Products.Archetypes.Field.StringField">TOP</ActionBarPosition>
      <HideDefaultActions type="Products.Archetypes.Field.BooleanField">False</HideDefaultActions>
      <HideInMenu type="Products.Archetypes.Field.BooleanField">False</HideInMenu>
      <isSearchForm type="Products.Archetypes.Field.BooleanField">False</isSearchForm>
      <isPage type="Products.Archetypes.Field.BooleanField">False</isPage>
      <SearchView type="Products.Archetypes.Field.StringField"/>
      <SearchFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></SearchFormula>
      <Position type="Products.Archetypes.Field.IntegerField"/>
      <excludeFromNav type="Products.Archetypes.Field.BooleanField">False</excludeFromNav>
      <elements>
        <element id="title_text" title="title_text" type="PlominoField">
          <id type="Products.Archetypes.Field.StringField">title_text</id>
          <FieldType type="Products.Archetypes.Field.StringField">TEXT</FieldType>
          <FieldMode type="Products.Archetypes.Field.StringField">DISPLAY</FieldMode>
          <Formula type="Products.Archetypes.Field.TextField"><![CDATA[if not isDocument(plominoDocument):
    return ''

if plominoDocument.isNewDocument() or plominoDocument.isEditMode():
    return ''

property_history_date = ''
last_modified_date = plominoDocument.getLastModified()
if last_modified_date:
    property_history_date = DateToString(last_modified_date, format='%d %B %Y %I:%M %p')

return property_history_date]]></Formula>
          <FieldReadTemplate type="Products.Archetypes.Field.StringField"/>
          <FieldEditTemplate type="Products.Archetypes.Field.StringField"/>
          <Mandatory type="Products.Archetypes.Field.BooleanField">False</Mandatory>
          <ValidationFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></ValidationFormula>
          <ToBeIndexed type="Products.Archetypes.Field.BooleanField">False</ToBeIndexed>
          <IndexType type="Products.Archetypes.Field.StringField">DEFAULT</IndexType>
        </element>
        <element id="today_date" title="today_date" type="PlominoField">
          <id type="Products.Archetypes.Field.StringField">today_date</id>
          <FieldType type="Products.Archetypes.Field.StringField">DATETIME</FieldType>
          <FieldMode type="Products.Archetypes.Field.StringField">EDITABLE</FieldMode>
          <Formula type="Products.Archetypes.Field.TextField"><![CDATA[return Now()]]></Formula>
          <FieldReadTemplate type="Products.Archetypes.Field.StringField"/>
          <FieldEditTemplate type="Products.Archetypes.Field.StringField"/>
          <Mandatory type="Products.Archetypes.Field.BooleanField">False</Mandatory>
          <ValidationFormula type="Products.Archetypes.Field.TextField"><![CDATA[]]></ValidationFormula>
          <ToBeIndexed type="Products.Archetypes.Field.BooleanField">False</ToBeIndexed>
          <IndexType type="Products.Archetypes.Field.StringField">DEFAULT</IndexType>
          <params>
<param>
<value><struct>
<member>
<name>format</name>
<value><string>%d %B %Y %I:%M %p</string></value>
</member>
</struct></value>
</param>
</params>
        </element>
      </elements>
    </element>
  </design>
</plominodatabase>