http://www.delphiarea.com/products/delphi-components/backgroundworker/
Background Worker Component (18.1 KiB, Last updated on December 6, 2008)
Source code of the TBackgroundWorker component, including the documentation and two sample programs.
TBackgroundWorker component is the Delphi implementation of .NET BackgroundWorker component.
TBackgroundWorker component allows you to run an operation on a separate, dedicated thread.
Time-consuming operations like downloads and database transactions can cause your user interface (UI)
to seem as though it has stopped responding while they are running.
When you want a responsive UI and you are faced with long delays associated with such operations,
TBackgroundWorker component provides a convenient solution.
To execute a time-consuming operation in the background, use TBackgroundWorker component
and listen for events that report the progress of your operation and signal when the operation is finished.