Just out of curiosity, how do you envision using a tweak like this? I see people asking for it a lot, but when I think about my inbox, I can't imagine a time when I want to delete every single mail in there. Am I just weird in that I don't delete every mail after reading it? (Mostly because gmail gives me so much free space that I don't need to, and can search it all later.) And if you do use it on your phone, won't the next 40 mails available from the server just take their place?
Or is this a tweak really meant for people who subscribe to the "Empty Inbox" way of handling mail?