nickjj's description was very clear:
> if you use tmux and have Vim open and try to click into Vim or any tmux window, nothing happens.
This means one of three things:
* tmux doesn't know to enable mouse reports, which will be almost certainly a TERM and terminfo configuration issue.
* The terminal emulator does not recognize the control sequences that turn on the various kinds of mouse reporting (DEC Locator, X10, Unicode rxvt, and ECMA-48-conformant XTerm).
* The terminal does not pass on mouse input events as mouse reports.
I shouldn't play the "mouse input events have been around for decades" card here, if I were you. DEC Locator reports precede anything relating to Win32, dating back to the VT220 in 1983. People could quite justifiably play the "Windows Terminal is not as good as a terminal from 1983" card in response. (-:
... and zamadatix did point to the known open issue on this. It's both the second and third items.