OnePlus 2 - Rooting and Multi-Window Mode

OnePlus 2 Rooting:

• I upgraded first (via OTA) to Marshmallow / Oxygen 3.0
• The ultimate guide is here: https://forums.oneplus.net/threads/oneplus-2-how-to-unlock-bootloader-install-custom-recovery-root-efs-backup-more.345478/
• After flashing TWRP and SuperSU, my OnePlus 2 kept boot-looping / getting stuck on the splash animation, so I had to troubleshoot.
• I found that the only working method (to gain root but keep Marshmallow / Oxygen 3.0) is to use Grarak's TWRP recovery and a modified SuperSU. I used these specific links:
• Grarak: https://www.androidfilehost.com/?fid=24572330218882108
• SuperSU: https://www.androidfilehost.com/?fid=24459283995297946
• If the above links no longer work, this post will probably be updated with the newest ones: https://forums.oneplus.net/threads/mirrors-for-official-oxygen-os-roms-and-ota-updates.387615/

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OnePlus 2 - Enabling Multi-Window Mode / True Multi-tasking:

• After using the OnePlus 2 for more than 5 minutes, I quickly realized just how big my new phone was. Coming from the Moto G, this phone feels enormous, and to be realistic, it is pretty big, even when compared to competitors. Thus, it felt really wasteful to have this huge screen and be only using it for one simple app at a time. I wanted to see if I could multitask, and specifically with multi-window mode.
• If you are rooted, this is actually incredibly easy.
• Guide: http://forum.xda-developers.com/android/general/guide-enable-multi-window-mode-android-t3121483
• My steps were even simpler; I simply installed the ROM Toolbox app (free), which let me edit my build.prop file in seconds to change the user type from "user" to "userdebug", then I rebooted, went into develop options, and turned on "multi-window".
  
  
• So far, most apps work fine with it, and it is great for using Gmail on one side and some other thing on another.