title: custom format or transform data in a MaskedTextBox during databinding
body: <p>I am looking for a way to display other data in a MaskedTextBox than the data it is bound to (DataTable).</p>
  
  <p>More specifically: The DataTable contains a DateTime column (DateOfBirth). Whenever the year is 1900, I would like to display it as empty in the MaskedTextBox while keeping it in the underlying DataTable, because I use 1900 for "unknown".</p>
  
  <p>Example: Value in the DataTable: 1900-10-09 --[DataBinding]--> MaskedTextBox <em>_</em>_-10-09</p>
  
  <p>Currently, I am using the CurrentItemChanged-Event of the BindingSource, to modify the Text-property of the MaskedTextBox. That works nicely as long as I simply browse through the DataTable. However, as soon as I start editing the MaskedTextBox, 1900 is back.</p>
  
  <p>It would be nicer if I could somehow intercept the value that is passed from the DataRow to the MaskedTextBox, instead of replacing it afterwards.</p>
  
  <p>Or maybe there is a way to get the MaskedTextBox to display 1900 as empty?</p>