Mode - screen windows. Ctrl+C - free mouse

We to press this combo "shift+U". Next... We to press this button "Up"(or other) and click left button for abroad window LFS. After... this camera go-go-go ahead)
I guess it's an old bug.

Well, that both could be considered as bug and not, well not in shift+u...

To reporduce this "bug" you should hold button "UP" and then without releasing it click with right click on LFS's title bar, while there is menu release "UP" key. This is basically same thing as "throttle stuck" as you reported some time ago
Thing is LFS doesn't receive WM_KEYUP message and therefore assume you are still holding button. Ofcourse there are way to get around those messages and solve the problem... Will see what Scawen think

It's annoying when it occurs.

Obviously nothing to do with shift+U.
You can also do it differently - while LFS is in window,take RB4 and drive out on carpark. Start doing doughnuts with full lock and full throttle. Click mouse outside LFS window. Go drink a tee or something. Come back and see RB4 still spinning on it's own.
With other words - whatever controls,buttons are pressed/used when clicking outside LFS window,they stay as long as you reactivate LFS window. Not sure if it can be described as bug,allthough it has a potential to cause incidents.

omg))