Hey guys, first things first, thank you so much for your help in other circumstances i've learnt a lot and that's why i got to having this question.
I've been checking my files with iFile and iPhone Browser, and i wanted to know if it was possible to change something inside an appstore app. I've already changed the icon with winterboard but I want to change the picture it displays when i use the app.
It's a one click call app, i want to change the default.png for a picture of my girlfriend by naming as default.png.
Can that be done or will it brick the app?

I know for some apps that can be done. I already change that on my GPS app.