>What would be the.net equivalent of the vfp textbox.programmaticchange event. Specifically I would like to apply a format on the .text at "loading" time, i.e. when bindingsource changes the underlying value of a bound control (textbox).

Assuming this is WinForms (rather than ASP.NET or WPF) then look at the Binding.Format event:http://msdn.microsoft.com/en-us/library/system.windows.forms.binding.format.aspx