sorry,
this is my code:

<asp:ObjectDataSource ID="odsEdit" runat="server" OldValuesParameterFormatString="original_{0}"
    SelectMethod="GetData" TypeName="dsTradCategorieTableAdapters.Trad_CategorieTableAdapter">
</asp:ObjectDataSource>
<ext:Store ID="storeEdit" runat="server" DataSourceID="odsEdit">
    <Reader>
        <ext:JsonReader ReaderID="IDTradCat">
            <Fields>
                <ext:RecordField Name="IDTradCat" />
                <ext:RecordField Name="IDCategoria" />
                <ext:RecordField Name="IDLingua" />
                <ext:RecordField Name="datains" Type="Date" />
                <ext:RecordField Name="descrizione" />
                <ext:RecordField Name="nomecat" Type="String" />
                <ext:RecordField Name="pagina" />
                <ext:RecordField Name="attivo" />
            </Fields>
        </ext:JsonReader>
    </Reader>
    <Listeners>
        <DataChanged Handler="var record = this.getAt(0) || {};#{frmEdit}.getForm().loadRecord(record);" />
        <BeforeLoad Handler="#{winEdit}.body.mask('Loading...', 'x-mask-loading');" />
        <Load Handler="#{winEdit}.body.unmask();" />
        <LoadException Handler="#{winEdit}.body.unmask();" />
    </Listeners>
</ext:Store>

<ext:Window ID="winEdit" runat="server" Title="Edit Traduzione Categorie" Icon="VcardEdit"
    Center&#111;nload="true" Width="700" AutoHeight="true" BodyStyle="padding:10px;" Collapsible="true"
    Resizable="true" Closable="true" Show&#111;nload="false">
    <Body>
        <ext:FitLayout ID="FitLayout1" runat="server">
                <Body>
                    <ext:HtmlEditor ID="descrizione" AllowBlank="true" MinValue="0" Height="190" 
                                        DataIndex="descrizione" runat="server" FieldLabel="Descrizione"
                                        ReadOnly="true" Width="500" MsgTarget="Side">
                                    </ext:HtmlEditor>

                     
                </Body>
                <Listeners>
                    <ClientValidation Handler="#{btnSave}.setDisabled(!#{frmEdit}.getForm().isValid());" />
                </Listeners>
            </ext:FormPanel>
        </ext:FitLayout>
if save record with HtmlEditor text is empty :(

regards