TextBoxWatermark(水印文本框)控件

功能：
    可以让TextBox控件拥有水印文字。
属性：
    TargetControlID :要使用具有水印效果的TextBox控件ID。
    WatermarkCssClass :指定水印文字的CSS样式表。
    WatermarkText :显示在TextBox控件的水印文字内容。

代码实例：

    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
  <asp:Panel ID="panIntTemp" runat="server" 
                            GroupingText="新增资料">
                            <table>
                                <tr>
                                    <td>
                                        姓名：
                                    </td>
                                    <td>
                                        <asp:TextBox ID="txtIntName" runat="server" ></asp:TextBox>
                                        
                                        <ajaxToolkit:TextBoxWatermarkExtender ID="tbweTxtIntName" runat="server"
                                            TargetControlID="txtIntName"                                            
                                            WatermarkText="请在此处输入姓名">
                                        </ajaxToolkit:TextBoxWatermarkExtender>
                                    </td>
                                    <td>
                                        性别：
                                    </td>
                                    <td>
                                        <asp:TextBox ID="txtIntGender" runat="server" ></asp:TextBox>
                                        
                                        <ajaxToolkit:TextBoxWatermarkExtender ID="tbweTxtIntGender" runat="server"
                                            TargetControlID="txtIntGender"                                          
                                            WatermarkText="请在此处输入性别">
                                        </ajaxToolkit:TextBoxWatermarkExtender>
                                    </td>
                                <tr>
                                    <td>
                                        出生日期：
                                    </td>
                                    <td>
                                        <asp:TextBox ID="txtIntBirthday" runat="server" ></asp:TextBox>
                                        
                                        <ajaxToolkit:TextBoxWatermarkExtender ID="tbweTxtIntBirthday" runat="server"
                                            TargetControlID="txtIntBirthday"                                           
                                            WatermarkText="请在此处输入出生日期">
                                        </ajaxToolkit:TextBoxWatermarkExtender>
                                    </td>
                                    <td>
                                        家庭住址：</td>
                                    <td>
                                        <asp:TextBox ID="txtIntAddress" runat="server"></asp:TextBox>
                                       
                                        <ajaxToolkit:TextBoxWatermarkExtender ID="tbweTxtIntAddress" runat="server"
                                            TargetControlID="txtIntAddress"                                            
                                            WatermarkText="请在此处输入家庭住址">
                                        </ajaxToolkit:TextBoxWatermarkExtender>
                                    </td>
                                </tr>                             
                            </table>
                        </asp:Panel>
    </form>

运行结果：