[0] https://www.apple.com/v/macbook-air/x/images/overview/mac-pl...
* Try to move space on such a device, the non-rounded desktop appears…
Running an Apple Studio Display here, and no rounded corners at any edges. So, just for non-Apple monitors?
Not sure what this tool’s function is supposed to be, given that the rounded corners only appear on screens that are actually rounded. Why would you want to straighten that out on a physically-rounded screen?
On the MBP built-in display, the upper-left and upper-right corners are rounded. I believe this is due to the shape of the display. The bottom corners are not rounded.
On the external displays, the corners are all square.
But most importantly, when connected to sharp-edged monitors, the Mac does not round the corners and instead displays the entire contents of the screen edge-to-edge (including the desktop and menu bar). So this tool seems to be solving a problem that does not exist.
There's software like Top Notch if you want to make the bottom corners rounded also.