Not sure about using target="_blank", but something I've done in the past is
go ahead and let the button post back as usual then add a startup script in
the button event handler (using RegisterClientStartupScript) to open a new
window using javascript. To pass the processed data, you can put it in an
object (or struct) and stuff it into the session, then read that session
variable from the page opened in the new window.

Just an idea. It may or may not work for your situation.

Hi,

  I did manage to do what you needed by addin the following line of
code to the OnClientClick of a linkbutton :

javascript:var aspnettarget;
aspnettarget=document.forms[0].target;document.forms[0].target='_blank';eval(this.href);document.forms[0].target=aspnettarget;
return false;

 I guess you understand what it does, but for others who might
wonder,

aspnettarget=document.forms[0].target;         keeps the default
Target of the normal ASP.NET Form
document.forms[0].target='_blank';                Changes the actual
target of the form to _Blank so it opens in a new window
eval(this.href);                                              does a
normal postback of the button to the new target
document.forms[0].target=aspnettarget;         Sets back the normal
Target for the ASP.Net Form
return false;                                                 Cancel
the "normal" call to the __Postback method since we already called it.

 It worked for me just as needed... Hope this helps.

Raphaël LEMIEUX

Hi,

  I did manage to do what you needed by addin the following line of
code to the OnClientClick of a linkbutton :

javascript:var aspnettarget;
aspnettarget=document.forms[0].target;document.forms[0].target='_blank';eva­
l(this.href);document.forms[0].target=aspnettarget;
return false;

 I guess you understand what it does, but for others who might
wonder,

aspnettarget=document.forms[0].target;         keeps the default
Target of the normal ASP.NET Form
document.forms[0].target='_blank';                Changes the actual
target of the form to _Blank so it opens in a new window
eval(this.href);                                              does a
normal postback of the button to the new target
document.forms[0].target=aspnettarget;         Sets back the normal
Target for the ASP.Net Form
return false;                                                 Cancel
the "normal" call to the __Postback method since we already called
it.

 It worked for me just as needed... Hope this helps.

Raphaël LEMIEUX