[Xiaomi Mi Max ROMs, Kernels, Recoveries, & Other D] nijel8:
That's SU icon and you can hide it in Status bar settings.

That's how it is. You don't wanna mess with /system...

That "lost messages" problem is probably due to "lost data after TWRP restore" fix... not playing well with f2fs!? Did you loose some settings as well like Development mode enabled, button brightness etc? B/c that is fixed for me on ext4 data...

WiFi got a speedup strangely? Did you check the changelog? Qualcomm missed 2.4 GHz mode in their config file and now it's fixed...

Camera... that's the hard part... I enabled API 2 during my tests and it didn't work for video despite Android reports hardware supports it. MIUI camera hal is old (API 1 only) and doesn't even support the new Android 7.1 cameraserver security features... Fixing camera is giving every device dev a hard time right now, some are moving to open source hal and try fixes. I am not sure if we will ever get fully functional camera... So many layers involved with it...

High speed recording works for 720p 120 fps, don't know what is the max size though:

General
Complete name : C:\Users\Nick\Desktop\VID_20170129_103823.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 30.6 MiB
Duration : 5s 440ms
Overall bit rate : 47.2 Mbps
Encoded date : UTC 2017-01-29 15:38:30
Tagged date : UTC 2017-01-29 15:38:30
com.android.version : 7.1.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Baseline@L5.0
Format settings, CABAC : No
Format settings, ReFrames : 1 frame
Format settings, GOP : M=1, N=120
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 4s 483ms
Bit rate : 56.1 Mbps
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Rotation : 90°
Frame rate mode : Constant
Frame rate : 120.000 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.507
Stream size : 29.8 MiB (97%)
Title : VideoHandle
Language : English
Encoded date : UTC 2017-01-29 15:38:30
Tagged date : UTC 2017-01-29 15:38:30
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Color range : Full
colour_primaries_Original : BT.601 NTSC
transfer_characteristics_Or : BT.601
matrix_coefficients_Origina : BT.601
mdhd_Duration : 4483

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 5s 440ms
Duration_FirstFrame : 1ms
Bit rate mode : Constant
Bit rate : 96.0 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Stream size : 64.1 KiB (0%)
Title : SoundHandle
Language : English
Encoded date : UTC 2017-01-29 15:38:30
Tagged date : UTC 2017-01-29 15:38:30
mdhd_Duration : 5440

... and 1080p 90fps as well:

General
Complete name : C:\Users\Nick\Desktop\VID_20170129_104728.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 8.38 MiB
Duration : 4s 779ms
Overall bit rate : 14.7 Mbps
Encoded date : UTC 2017-01-29 15:47:34
Tagged date : UTC 2017-01-29 15:47:34
com.android.version : 7.1.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Baseline@L5.1
Format settings, CABAC : No
Format settings, ReFrames : 1 frame
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 1s 56ms
Bit rate : 60.0 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Rotation : 90°
Frame rate mode : Constant
Frame rate : 90.000 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.321
Stream size : 7.55 MiB (90%)
Title : VideoHandle
Language : English
Encoded date : UTC 2017-01-29 15:47:34
Tagged date : UTC 2017-01-29 15:47:34
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Color range : Full
colour_primaries_Original : BT.601 NTSC
transfer_characteristics_Or : BT.601
matrix_coefficients_Origina : BT.601
mdhd_Duration : 1056

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 4s 779ms
Source duration : 4s 795ms
Source_Duration_FirstFrame : 16ms
Bit rate mode : Constant
Bit rate : 96.0 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Stream size : 56.4 KiB (1%)
Source stream size : 56.4 KiB (1%)
Title : SoundHandle
Language : English
Encoded date : UTC 2017-01-29 15:47:34
Tagged date : UTC 2017-01-29 15:47:34
mdhd_Duration : 4779

Slow motion 720p 120 fps works too, recorded file reports 30 fps, plays at slow motion. But don't really know what it should report or look like...

So looks like those works for me but don't know if they work as they should, what's are the limits etc...