Some time has passed and I’ve at least found the time to add native 4:3 and 21:9 support to the skin now.
You can check this out by following these instructions:
- Login via the command line
- Edit the file
/etc/apt/sources.list - Add the following line:
deb http://apt.osmc.tv stretch-devel main - Run the following commands to update:
sudo apt-get update && sudo apt-get dist-upgrade && reboot - Your system should have have received the update.
I also recommend you edit /etc/apt/sources.list again and remove the line that you added after updating. This will return you to the normal update channel.
Masking to 2.35:1 and 2.40:1 with 16:9 output is next on the list. It’s a lot harder to do as one output mode (16:9) has to have a toggle and two sets of hight information for each and every control. Plan is to limit all controls to a 1920x800 window and offer black masking bars on the top and bottom. I’m not offering any ETA on this as it will require quite some work. But I’ll do my best to implement it 
Making our skin one of the most versatile out there is a challenge I gladly accept. 