Yes. The Mini Editor box that pops up does accept BBCODE so I’m thinking that the Highlight button could, right inside the mini-box, just wrap the selected text inside a bbcode like this
[bgcolor=#ff8]this text would then have a yellow background[/bgcolor]
@merefield’s tidy little TC might be able to be used – I’m looking at it…
If we wanted to go fancy, the button could pop up a tiny bbcode toolbar like this…
https://www.phpbb.com/customise/db/extension/advanced_bbcode_box/