Pop up on exit

Hi,

I would like to get a pop up box to show when the user saves and exits a spreadsheet.

I dont want the user to have to select cancel or ok, just for the window to show for say 10 seconds.

Is this possible?

The reason i dont want any user input is the sheet has an auto close where is shuts down if not used for 15mins and dont want it to interfere with that. Just when the user selects to close the sheet.

Many thanks