In ImageGear for Silverlight TWAIN, when a Data Source's UI is open and the user clicks the cancel button (or any other button which sends MSG_CLOSEDSREQ) an exception will not be thrown. In this case, the method will return a null value.

The behavior for ImageGear .NET TWAIN is different; in this case, an ImGearException with the error code TWAIN_OPERATION_CANCELED is thrown.

Note that this behavior is not dependent on how the Data Source's UI was shown. In other words, the behavior does not vary within a product (ImageGear .NET or ImageGear for Silverlight) if the UI was shown by calling ImGearTWAIN.ShowSourceUI() or by calling one of the ImGearTWAIN.Acquire* methods (ImGearTWAIN.Acquire, ImGearTWAIN.AcquireToPage, ImGearTWAIN.AcquireToDoc).