Getting value back from Modal PopUp

I have a ModalPopup in the ItemTemplate of a GridView like

<ItemTemplate>
  <asp:LinkButton ID="lnkbtnSeek" CommandArgument='<%# Eval("ID") %>' runat="server" Text= "Info" CommandName="Seek" />
  <asp:Panel ID="pnlProject" runat="server" Style="display: none" CssClass="ModalPopupPa开发者_高级运维nel">
    <div style="float: right;">
      <asp:LinkButton ID="lnkClose" runat="server" Text="Close" />
    </div>
    <asp:Label ID="lblDescription" runat="server" Text="Give Description" /><br /><br />
    <asp:TextBox ID="txtDescription" runat="server" Height="150px" Width="100%" TextMode="MultiLine" />
    <br />
    <asp:Button ID="btnSubmit" OnClientClick="<% %>"  runat="server" Text="Submit" CommandArgument='<%# Eval("Id") %>' OnCommand="btnSubmit_Click" />
  </asp:Panel>   
  <asp:ModalPopupExtender id="extProject" runat="server" targetcontrolid="lnkbtnSeek" popupcontrolid="pnlProject" dropshadow="true" backgroundcssclass="ModalPopupBackground" cancelcontrolid="lnkClose" />
</ItemTemplate>

Now when click on btnsubmit I want to get the txtDescription value in button command event. Else every thing is working fine. On pressing Info Linkbutton I am able to popup the modal popup and on button click able to do the work(else that textbox data). Also only able to call Gridview_RowCreated event not others even Gridview_RowCommand event is not firing. But events I don't need if I can get the value of that txtbox in somewhere.

How to get that?

Thanks.

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Inside of your btnSubmit_Click event, you have the particular button that was clicked:

Button btnSubmit = (Button)sender;

Then you can navigate from there

TextBox txtDescription = btnSubmit.Parent.FindControls("txtDescription") as TextBox;

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You must pass refernce in when you open the dialog:

var vReturn = window.showModalDialog(<url here>, self, <features here>);

In your modal dialog page have the following code:

var opener = window.dialogArguments;