an option for bar to overlay windows, like dmenu

## I'm submitting a…

[ ] Bug

[x] Feature Request

[ ] Documentation Request

[ ] Other (Please describe in detail)

## Current Behavior

as expected and designed moves windows to not overlay them.

## Desired Behavior

overlay windows and cause them to change bounds.
I prefer toggling the status bar with a keyboard binding to take a peek when I want to, and I would prefer also if it overlayed the windows and didn't cause them to change bounds and relayout/+repaint.

dmenu/dmenurun overlaying:


## Environment

Output of `i3 --moreversion 2>&-`:

Binary i3 version:  4.17.1 (2019-08-30) © 2009 Michael Stapelberg and contributors

(Getting version from running i3, press ctrl-c to abort…)

Running i3 version: 4.17.1 (2019-08-30) (pid 698)

Loaded i3 config: /home/x/.config/i3/config (Last modified: Wed 08 Jan 2020 07:34:56 PM IST, 918 seconds ago)


The i3 binary you just called: /usr/bin/i3

The i3 binary you are running: i3

- Linux Distribution & Version: Linux archiver 5.4.8-arch1-1 #1 SMP PREEMPT Sat, 04 Jan 2020 23:46:18 +0000 x86_64 GNU/Linux

- Are you using a compositor (e.g., xcompmgr or compton): xcompmgr