The following example shows difference between input control that uses ClearErrorOnTextInput and input controls that does not use ClearErrorOnTextInput.

<Intersoft:FieldLabel Header="Price:" HeaderWidth="80" HorizontalHeaderAlignment="Right">
    <Intersoft:UXTextBox HorizontalAlignment="Center" Width="60" 
                            Text="{Binding Path=Book.Price, Mode=TwoWay, ValidatesOnDataErrors=True, ValidatesOnExceptions=True, StringFormat=\{0:c\}}"/>
</Intersoft:FieldLabel>

<Intersoft:FieldLabel Header="Price:" HeaderWidth="80" HorizontalHeaderAlignment="Right">
    <Intersoft:UXTextBox HorizontalAlignment="Center" Width="60" 
                            Text="{Binding Path=Book.Price, Mode=TwoWay, ValidatesOnDataErrors=True, ValidatesOnExceptions=True, StringFormat=\{0:c\}}"
                            Intersoft:DataBinding.ClearErrorOnTextInput="True"/>
</Intersoft:FieldLabel>

ClearErrorOnTextInput is one of many functionality provided in ClientUI Advanced Binding Framework. To learn more about this see Data Binding Overview.

ClearErrorOnTextInput is an attached property that you can used to enhance validation behavior. The standard validation behavior gives an error indication when the validation failed and stays visibile until a new validation takes place.

ClearErrorOnTextInput provides an enhanced behavior where you can clear the error indication immediately when you perform any text input.

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

DataBinding Class
DataBinding Members

Concepts

Data Binding Overview