Feature: 4:3 Fullscreen Borderless

[BJack0]

Which component should be improved?

Rendering

Describe your feature suggestion in more detail

Games like Rainbow Six Siege can run 4:3 resolution and render the game in 4:3 aspect ratio while still maintaining windowed borderless tabbing.

Ideally I'd like to set my resolution to 1440 x 1080, 4:3 aspect ratio and still be able to tab out of my game without it being forced to minimize.

[BJack0]

Bumping this as Valve just added this feature to CS2 in the latest update. Obviously I don't know if this is exclusive to source 2, but it's a massive QoL improvement.