I use to be able to send flash messages from my N95 8gb Symbian and was wondering if anybody else is looking for a similar app for their lumia 1520 WP8 perhaps some clever developer out there will help us solve this problem.
no no no.
flash sms is nothing to do with flash or .swf
flash sms is a sms, which is displayed completely and directly on ur screen, rather that going in inbox or threads. then when u hit the back key, it gets deleted automatically. u won't find it in inbox or threads. some older phones shown receiving flash sms in their logs, but most of the phones, cannot.
thus, flash sms is not traceable once deleted.