Don't like it when nobody answers… So I will be the bearer of not so good news… I thoughts are there are 2 types/levels of app dialogs warning & error the first you can dismiss as your example… The second you might be able to wrap in a try, catch, finally… I know that for Photoshop several scripters said they would prefer script not to stop… and throw the error… Do you have many files that will be like this ( never had this dialog myself ) Single out specific errors may be CS8…
I already tought so, but i needed to know for sure... I do not have much documents like this but i wrote a script that generates pantone color sheets to calibrate my printers to print better pms colors. This will generate this error but will still run!
Bookmarked it for now will have to check it out some other time… Must say do like your UI you have done a good job of that…