UPDATE: This has nothing to do with tmux. I only had not used vim enough without it to see the errors I am reporting here.
Every few minutes while working with vim, putting the editor on background bringing it back up to the foreground, running tests, editing here and there, the rendering gets messed up, like, columns unaligned text over... hard for me to explain, but if you had the experience you probably know what I mean.
The image below sort of exemplifies what I mean. See the weird chars on the right hand side. It does not look like, but vim is in the foreground. You can see the "recording @q" which I accidentally start too often. It seems it does not happen when I use vim outside of tmux.
I usually get this fixed by hitting Ctr-V a few times and putting the editor in the forgeground and background a few times, or simply typing reset.
This is very annoying and it will take me a while to debug, unless someone already managed to fix it :)
Here is my tmux config file https://github.com/mjacobus/.dotfiles/blob/master/tmux/tmux.conf
Here are my vim scripts https://github.com/mjacobus/.dotfiles/tree/master/vim
I use it on ubuntu 18.4, the "terminal" terminal.
Thank in advance for all your tips.