ASP.NET C#: ModalPopup flicker on server validation postback.

[pechar]

I've posted this in the AJAX section but was told I'll have more luck here so :

Hi all,

First of all I've searched the net but with no luck. My problem is I have a master/detail webform. i.e. the user clicks a record from the list and I show a modalpopup with the data. Here the user can edit this data. Apart from clientside validation I have some server validation (which I need).
In the (server) Click event of the submit LinkButton I have the following:

     protected void lbtnSave_Click(object sender, EventArgs e)
 
              {  
                  if (Page.IsValid)  
                  {  
                              //save changes     
                  }  
                  else  
                  {  
                      //show the popup again since after postback it is hidden  
                      modalPopupExtender.Show();  
                  }  
              }
 

Everything, like the validator values remain there which is as I need it and all the functionality is there. The only problem I have is there is a flicker (from reload of modalpopup) after postback.

I tried putting it all into an UpdatePanel but with no luck.

Is there a way I could make a partial postback or maybe call postback from clienside? If yes could you please explain how this could be done? Also any code snippets are very welcome (I'm quite new to AJAX, especially Javascript)

Thanks
Luk