I just looking in couple framework. and just curious what they use to bind the UI is using
! IsCallback instead of ! IsPostback
Just making summary out of this
IsCallBack will be set to true if you doing a partial postback.
if you checking using IsCallBack and there is no ajax call , it will not affect anything. Just similar like you don't use the checking which is doesn't improve your performance.
But there should be a reason behind it, or probably they have a mistype because of Autocomplete provided by VS =p