download 2 jb roms and then copy lets say clock.apk from one to other and flash it to my phone without any problems?
it depends ROM to ROM. I tried to bring back the ICS Clock to JB and it did not work. I think (and others can correct me if i am wrong) the roms would have to be the same Version (4.2.2... ect) for them to work.
I still concider myself a noob with a lot of this stuff.
All u need to do is copy the apk u want to install to the system/app folder, change permissions, and reboot. The app should show up in your drawer after that. Remember to make a back up 1st just in case the apk decides it doesn't want to make nice with the ROM u are on
Sent from my XT894 using Xparent Skyblue Tapatalk 2
Find us on Google+