I'm connecting an Apple Bluetooth Aluminum keyboard (this one) to my Lubuntu setup using the blueman applet.

The keyboard types fine, but I would like to use its fn key to change screen brightness changing, page-up (fn+ctrl+down), page-down (fn+ctrl+up), et cetera. Right now the fn key doesn't seem to work.

When I use xev, I don't see anything happen when I press fn.

Does the keyboard not send this to the computer at all?

Do I need to configure blueman's "Input Service" setting to make this an Apple (rather than a generic) keyboard? (It's not obvious how to do this.)

Is xev just not showing the fn key?

Where in this stack of software do I need to make a change to achieve the desired behaviour?

Thanks!