ABL provides a shadow window solely to enable forms and windows to parent each other in an ABL session. A shadow window has no visualization and has only one attribute, the PARENT attribute, which you can use to parent the associated form to another form or window. Note that the ABL virtual machine (AVM) creates a shadow window for each Progress.Windows.Form object that you create in a session and destroys the associated shadow window when the form closes, either by the user or programmatically using the Close( ) method on the form. You cannot explicitly create or delete a shadow window on a form's ProWinHandle property, and any attempt to do so raises a run-time error. For more information on using the shadow window of a form to parent forms and windows, see Parent forms and windows to each other.