Public cursors is a Polus feature where you can see others' cursors.
Usage
To enable the feature, click Enable cursors in the leftbar. Doing so will reveal 2 further options: All cursors lets you see who is on Polus and also has cursors enabled, and clicking on their name will start following them, and Info just links to this page.
To chat, press ' and start typing. Your message will immediately be transmitted to others viewing as you type. To clear the message, press Enter, and to stop chatting, press Esc.
If you prefer to keep your activity private, you can simply not enable the feature, but in that case, you also won't be able to see others' cursors.