Automating a message through Facebook Messenger

[Spask]

I'm trying to create a script that would send a message through facebook messenger invisibly. It should happen in the background without interfering with other windows. I will be logged into facebook already, so the login will be done manually. The only way I know of to automate this is by activating the window and sending simulated keystrokes, but the window needs to be active for that. I've also looked in the HTML to try to do it through that, but I wasn't able to find anything useful. How would I do this? Is it even possible?

[EmilyLove]

https://www.autoitscript.com/autoit3/docs/intro/controls.htm

This will let you automate a window that is not focused.

https://www.autoitscript.com/autoit3/docs/functions/WinSetState.htm

This will let you hide the window.

[Spask]

Thanks, very useful.