An NSNumber object containing a Boolean value that determines if validation and error alert panels displayed as a result of this binding are displayed as application modal alerts. If YES, then the alerts are displayed application model, otherwise they are displayed as sheets.
Available in Mac OS X v10.4 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)