Client-Side Progress Window

[FlashMerlot]

Are our users more-or-less stupid than average users?
We've been told our web application must give INSTANT visual feedback to the user when the user should STOP and wait for a refresh, postback, navigation to finish ....
Bottom line ... we need to execute Client-Side JavaScript at TWO exact moments during a Page life cycle ... How?

Moment A - The instant a page starts a server trip whether it's a postback, navigation to another page, or any other action which describes that moment when the user should stop all activity and wait for a new page or postback to complete.

Moment B - When a Page has finished receiving all content from the server and is completely done rendering itself and is now ready for user interaction.

Thanks

P.S. At Moment-A we intend to open a named dialog window saying "One Moment Please" and at Moment-B we'll find and close the dialog window.
Also, our policy says we need only support IE 5.5 and above.

 

[MOrac]

Make an onUnload event pop a floating div over the center of the browser window with your message in it, or in extreme cases hide the entire window's contents from the display first just to make sure there are no buttons or links left visible anywhere for the clicking...

Demo code should be fairly simple if needed.