文章出处：http://asp.net/ajax/documentation/live/tutorials/UpdateProgressTutorials.aspx
Introduction
The topics in this section provide examples of using the UpdateProgress control to display status during the partial-page rendering.
In This Section
- Introduction to the UpdateProgress Control
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Provides examples of how to use one UpdateProgress control to show partial-page update status for all UpdatePanel controls on the page, and two UpdateProgress controls to show status for different UpdatePanel controls.
- Programming UpdateProgress Controls in Client Script
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Provides examples of how to customize the behavior of the UpdateProgress control with script to cancel asynchronous postbacks and to toggle visibility of the progress message.
