I use tmux splits (panes). Inside one of these panes there's a Vim process, and it has its own splits (windows).
In Vim I have key bindings C-h/j/k/l set to switch windows in the given direction. (Vim default mappings for windows switching are the same, but prefixed with C-W.) I'd like to use the same keystrokes for switching tmux panes.
An extra goal that I've solved with a dirty hack is to toggle between last active panes with C-\.
Here's how it should work: