I'm curious what tricks and techniques you all have developed for maintaining the state of data on a form.

In the case of lots of textboxes, for instance.

How do you track the values - such as the value from the DB, value of the textbox currently, value of the textbox after change. Value as typed - value as displayed with edit masks...

Whether the textbox currently contains invalid data - whether it's been changed...

Whatever you all need to track for state - how do you store and reference that.