I have a couple of applications which I install as "system apps" by moving the apks from /data/app to /system/app (AltDrawer and Google Search renamed to QuickSearchBox). I'm sure everyone has their favorite set of apps they do this with. I've found that I have some troubles with these apps after upgrading the MIUI ROM, probably because the /system/app .apk file gets wiped out. Recovering is not a big deal, I install/uninstall/install and move to system area again. I'm wondering though whether there is a better way to do this? Just move the .apk back to /data/app before upgrading? Write a script to run before upgrading and then after upgrading? Are there hooks in the miui upgrade process for user written pre and post scrips? For now I've just stopped taking the weekly builds unless there is something interesting in the change log.