General :: How To Apply Themes Without Restarting Like Chameleon And MiUi

All the threads that I see for applying system wide, they would replace the framework-res.apk and SystemUI.apk and thus would require a restart of the device from the recovery mode.

However, the ROMs like MIUI and ChameleonOS does it without a restart.

Even few Old ICS devices used to come prebundeled with 2-3 Themes with different wallpapers and launcher default widgets.

I'm trying to do something on the lines of above ROMs and have started checking their code. And found that the starting point is by appending an extra path with the AssetManager, but since they also do a lot of changes to other applications,

would be great if I can get some pointers on where to start, key things to do to get the ball rolling and if there is already some solution like this which I can add to my ROM