terminal paste protection : why not at browser level?

Nice idea, though it would be great to have it implemented either at the desktop environment/window manager level, or at the X/Wayland level---that way it would apply to all applications that write to the clipboard, and it wouldn't be each application's responsibility to implement it separately.

Something like: if the user copies some text that contains control characters or other nasties, the window manager could throw up some kind of alert window telling them so. It would be nice to have the range of troublesome characters configurable, too---for example, Hebrew or Arabic-speaking users might commonly be copying U+200F RIGHT-TO-LEFT MARK, but other users might want to be warned about it.

I'm not sure how widely welcomed this would be, though. For users who never run a terminal emulator, this feature seems mostly useless.