title: Cannot show Modal popup extender after radgrid filter command
body: <p>I have a control that is displayed in Modal popup extender. This control contains RadGrid element. I had to create a custom filter using FilterTemplate and I get a postback call with correct command name set. However, Modal popup extender doesn't display Show() method being called.</p>
  
  <p>Perhaps it is best to show it with code.</p>
  
  <p>Modal popup extender on default.aspx:</p>
  
  <pre><code>&lt;asp:Panel ID="pmpSetDostopIS" runat="server" Width="80%" Height="80%" ScrollBars="Vertical" CssClass="modalPopup" Style="display: none"&gt;
      &lt;div align="center"&gt;
          &lt;asp:Label ID="Label2" runat="server" Text="DostopIS" Font-Bold="True"&gt;&lt;/asp:Label&gt;    
      &lt;/div&gt;                            
      &lt;hr /&gt;
      &lt;asp:Button ID="btnShowPopupSetDostopIS" runat="server" Style="display: none" /&gt;
      &lt;asp:ModalPopupExtender ID="pmpDostopISExtender" runat="server" TargetControlID="btnShowPopupSetDostopIS"
          PopupControlID="pmpSetDostopIS" BackgroundCssClass="modalBackground" DropShadow="false"&gt;
      &lt;/asp:ModalPopupExtender&gt;
      &lt;uc7:ppDostopISEdit ID="ucdeDostopIS" runat="server" /&gt;
  &lt;/asp:Panel&gt;
  </code></pre>
  
  <p>ppDostopISEdit.ascx:</p>
  
  <pre><code>&lt;telerik:RadGrid ID="rgDostopISLotusNotes" AllowMultiRowSelection="True" AllowPaging="False" AllowSorting="True" AllowAutomaticDeletes="False" 
      DataSourceID="odsLNDostop" EnableLinqExpressions="false" GridLines="None" runat="server"&gt;
      &lt;MasterTableView AutoGenerateColumns="False" AllowFilteringByColumn="True" TableLayout="Fixed" DataKeyNames="SLNS_ID_LN_SKUPINA" DataSourceID="odsLNDostop"&gt;
          &lt;Columns&gt;
              &lt;telerik:GridTemplateColumn AllowFiltering="false" UniqueName="SELECTION"&gt;
                  &lt;HeaderStyle Width="30px" /&gt;
                  &lt;HeaderTemplate&gt;
                      &lt;asp:CheckBox id="chkbxLNAll" OnCheckedChanged="chkbxLNAll_CheckedChanged" AutoPostBack="True" runat="server"&gt;&lt;/asp:CheckBox&gt;
                  &lt;/HeaderTemplate&gt;
                  &lt;ItemTemplate&gt;
                      &lt;asp:CheckBox id="chkbxLNSelect" Checked='&lt;%# Bind("CHECKED") %&gt;' OnCheckedChanged="chkbxSelect_CheckedChanged" AutoPostBack="True" runat="server"&gt;&lt;/asp:CheckBox&gt;
                  &lt;/ItemTemplate&gt;
              &lt;/telerik:GridTemplateColumn&gt;
              &lt;telerik:GridBoundColumn DataField="NAZIV" HeaderText="Skupina" SortExpression="NAZIV" UniqueName="NAZIV" AutoPostBackOnFilter="false" CurrentFilterFunction="Contains" FilterControlWidth="200px" FilterDelay="500" ShowFilterIcon="true"&gt;
                  &lt;ItemStyle Wrap="False" /&gt;
                  &lt;FilterTemplate&gt;
                      &lt;telerik:RadScriptBlock ID="RadScriptBlock1" runat="server"&gt;
                           &lt;script type="text/javascript"&gt;
                               function filterLnGrid(sender, args) {
                                   var strKey = args.get_keyCode();
                                   if (strKey == "13") {
                                       var tableView = $find("&lt;%# CType(Container, GridItem).OwnerTableView.ClientID %&gt;");
                                       tableView.filter("NAZIV", sender.get_value(), "Contains");
                                   }
                               }
                           &lt;/script&gt;
                       &lt;/telerik:RadScriptBlock&gt;
                       &lt;asp:Literal runat="server" Text="Išči"&gt;&lt;/asp:Literal&gt;
                       &lt;telerik:RadTextBox runat="server" Text="" ClientEvents-OnKeyPress="filterLnGrid" AutoPostBack="false"&gt;&lt;/telerik:RadTextBox&gt;
                   &lt;/FilterTemplate&gt;
               &lt;/telerik:GridBoundColumn&gt;
          &lt;/Columns&gt;
      &lt;/MasterTableView&gt;
      &lt;ClientSettings EnableRowHoverStyle="true"&gt;
      &lt;/ClientSettings&gt;
  &lt;/telerik:RadGrid&gt;
  </code></pre>
  
  <p>ppDostopISEdit.ascx.vb (excerpt):</p>
  
  <pre><code>Protected Sub rgDostopISLotusNotes_ItemCommand(ByVal sender As Object, ByVal e As GridCommandEventArgs) Handles rgDostopISLotusNotes.ItemCommand
      Call m_pmpExtender.Show()
  End Sub
  </code></pre>
  
  <p>Now I am stuck, as the same thing works for a custom command on some other RadGrid.</p>
  
  <p>Edit:</p>
  
  <p>Further debugging showed that this is double postback problem. However, both postbacks are issued by this very same RadGrid. One is for Filter ItemCommand, the other is not, so I am assuming that it is caused by applying a filter to RadGrid.</p>