About the only thing I can think of is to hook into the "before uninstall" event, display your question, and if they say "no" then make a backup table of the plugins data, you'd then want to check for the backup in before install ( and ask the user if they want to re-use the backup )

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I was thinking I could do a faileduninstall and then do some js hacks to get rid of the error message and display a "Would you like to remove the data and files as well? Yes / No".

that'd be adding fluffy bits, and I leave fluffing to scott ;)

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