Feature: window fences

[Björn Fischer]

Hi folks,

> (i tried adding fences as an 'array' or as 'empty' (empty was
> documented in your PR, the code about fences said explicitly it
> needed to be an array, tried both... no avail)

while I am interested in this feature, too, I was not able to get it
working.

Enrico, maybe you can provide some example config?

I also have a draft merge request implementing advanced tiling
techniques in a different way:

https://gitlab.xfce.org/xfce/xfwm4/-/merge_requests/35

My implementation is lacking multi monitor support and usage
without a Compositor is somewhat ugly. Yet I did not receive any
feedback on my suggestions.

Cheers
Björn