Trill lines

I’ve found the section in the Dorico 4 online manual which discusses trill lines, but what is described as appearing in the properties panel is not what I’m seeing on my screen. The manual says that Dorico can be in either Write or Engrave mode to lengthen the trill line.
I have a trill over a dotted quarter note in 6/8 time and I would like to extend the line. When I select the trill, and have the properties panel open in either Write or Engrave mode the online manual says
" 1. In the Properties panel, activate/deactivate Has trill line in the Trills group." There is no such group showing in the Properties panel. All that shows for me are “Common” and “Playing Technique.”
I entered the trill by hitting shift-P (playing technique) and typing trill and then selecting Trill Key (the only thing which appeared with the word “trill”). Is there another way to enter a trill, one that is editable? In a response to a different message Daniel has said to click the end of the trill line and drag it to lengthen it, but when I try that the whole trill symbol moves. I’ve gone through the trill setting in the ornaments section of Engraving rules and the line is definitely enabled there.
What am I doing wrong?
Thanks for any help you can offer on this.

Trills are entered from the Shift-O popover or the Ornaments panel. I’m not entirely sure what you’ve entered but it doesn’t sound like the right one.

Thanks – I don’t know why I didn’t think that ornaments weren’t playing techniques and would have their own popover. I wonder why a non-functional “tr~” symbol is possible in the shift-P popover.

Oh well, I’ve just got so much more left to learn about Dorico!
Thanks again!

Trill keys exist on various wind instruments - I guess the Playing Technique you’ve stumbled upon is an indication that a wind player should make use of the trill key.

Hmm . . . good guess – I don’t have a better explanation.
I appreciate that you’ve made me aware of the shift-O ornament popover, so I should be all set with future ornament issues.

Thanks!