[feat] get the size of the taskbar

[mondy]

Describe the problem

I would like to get the size and location of the taskbar.
I'd like to see cross-platform support (Windows, Mac, Linux).
Using this, we would like to create a function that will pull the window to the edge when it comes to the edge of the screen.

Describe the solution you'd like

I think adding taskbar position and size information to the Monitor class would be a good idea, but there may be a better way.

Alternatives considered

I asked a question in the discussion and the following method seems to solve the problem in Windows.
#1336 (reply in thread)

Additional context

No response

[09silverware]

Kinda hard to ensure buttons for a always-on-top interface land above the taskbar without this feature.
Hopefully it gets implemented.

Doing some quick research to assist:

Mac Solution:
https://developer.apple.com/documentation/appkit/nsscreen/1388369-visibleframe?language=objc
Source: rust-windowing/winit#2494 (comment)

X11:
_NET_WORKAREA is a option for single monitors.
https://specifications.freedesktop.org/wm-spec/1.4/ar01s03.html#idm139704063854592
Source: https://stackoverflow.com/a/26524483

But it apparently falls down for multi-monitor setups.
Source: https://stackoverflow.com/a/18678545

[09silverware]

Quick and dirty solution.
Move a transparent, decoration-less window to the screen you want.
Create it at any size, but not maximized (to avoid the transparency issues in TAO atm).
In Rust, during setup, move to the monitor you want to measure, maximize, read size and position.
Then you can compare this against the monitor's size and position.

[Andrew-web-coder]

@09silverware But how can you maximize to fill area without taskbar? Because, if, you call .maximize() in Rust and then measure the size, it fills entire screen.

[Penguin-Guru]

I found this discussion because I was just working on a similar problem. I'll include a link to my commit in case it's useful to anyone here. My system doesn't seem to support _NET_WORKAREA, so I wasn't able to test that approach. If anyone wants to test it, I included a best guess at that approach in my code too.

Penguin-Guru/WallpaperChanger@5128d4b

[Legend-Master]

Implemented in #13276