I like messing around with things, and I discovered that if you open up a private chat window and type
where targetusername is the username of the person who's private chat window you've opened. It will send a blank message
For example, If I open up a chat window to ask-vinay, and type
he'll get an alert that I have typed something, while I haven't. The window will remain open.
It's very useful for when you want someone to talk to you but don't want to start the conversation