My cheap-ish Samsung (cheap for a QHD) has an HDMI and a DisplayPort input. If I hook up a laptop to each input, both laptops think the screen is on- even the one who is not currently being displayed.

While computer monitors seem to be more or less the same once you get past the size and the ports, that’s not really true. Even the most common type, the humble LCD, has a lot of sub-types. And while ...