Read original post at Johan Silfversparre's Blog
A common way to handle state on a page is to control the visibility of different UI areas by using properties in the view model without or in a combination with a converter. It can be both frustrating and time consuming for a UX developer to manually change view model properties each time the result of a state combination needs to be validated or edited.
My recent Windows Phone app T3XT K1NG is a one-page app where all the magic is happening on the main page. It allows the user to type text, open popup windows, start conversions, swipe buttons and more. All these UI states can easily lead into a complex and error-prone code.