有关GridView中ImageButton控件后台代码弹出对话框如何写
这是我前台的 <asp:GridView> 的相关信息，其中<asp:ImageButton ID="ImageButton2" CommandName="UserUpdate" runat="server" ImageUrl="~/images/edit.PNG" CommandArgument='<%# Eval("userid") %>' /> 这句是用来转向修改界面的。

  <asp:GridView ID="gvUserManage" runat="server" AllowPaging="True" Width="100%" CellPadding="1"
  BorderWidth="1px" AutoGenerateColumns="False" RowStyle-HorizontalAlign="Center"
  CssClass="GridViewStyle" PageSize="10" OnRowDataBound="gvUserManage_RowDataBound" 
  OnRowDeleting="gvUserManage_RowDeleting" 
  onrowcommand="gvUserManage_RowCommand"> 
   
   
  <PagerStyle CssClass="GridViewPagerStyle" />
  <HeaderStyle CssClass="GridViewHeaderStyle" />
  <RowStyle CssClass="GridViewRowStyle" Height="25px" />
  <AlternatingRowStyle CssClass="GridViewAlternatingRowStyle" />
  <PagerSettings FirstPageText="首页" LastPageText="最后 1 页" NextPageText="下 1 页" PreviousPageText="上 1 页"
  Mode="NumericFirstLast" />
  <EmptyDataTemplate>
  <font size="4pt">无数据！</font></EmptyDataTemplate>
  <Columns>
  <asp:TemplateField HeaderText="序号">
  <HeaderStyle HorizontalAlign="Center" Width="40px"></HeaderStyle>
  <ItemTemplate>
  <%# gvUserManage.PageIndex * gvUserManage.PageSize + gvUserManage.Rows.Count + 1%>
  </ItemTemplate>
  </asp:TemplateField>
  <asp:BoundField DataField="USERNAME" HeaderText="用户名" SortExpression="Sex" ItemStyle-HorizontalAlign="Center">
  <ItemStyle HorizontalAlign="Center"></ItemStyle>
  </asp:BoundField>
  <asp:BoundField DataField="USERJC" HeaderText="登录名" SortExpression="Sex" ItemStyle-HorizontalAlign="Center">
  <ItemStyle HorizontalAlign="Center"></ItemStyle>
  </asp:BoundField>
  <asp:BoundField DataField="rolename" HeaderText="角色" SortExpression="Sex" ItemStyle-HorizontalAlign="Center">
  <ItemStyle HorizontalAlign="Center"></ItemStyle>
  </asp:BoundField>
  <asp:TemplateField HeaderText="操作" ItemStyle-HorizontalAlign="Center">
  <ItemTemplate>