Hidden Controls and ViewState

I don't know if it is obvious how important ViewState is for hidden controls. I would like to stress where ViewState plays important role for hidden controls (not visible) as it often leads to not obvious problems. If you like to explore how different ASP.NET controls use ViewState to store their data, Nikhil Kothari's Web Development Helper is a very helpful tool. I definitely recommend to download and install it, if you like to know what is in your ViewState. TextBox when placed on a web form usually does not require ViewState to be enabled to provide its core functionality "being input box". You can check that __VIEWSTATE hidden field is the same across post-backs if you change the value in your TextBox on the following form: