Sorry for another trivial question, but I have searched and not found an answer..
I set up a Lister Style to have Dual Display, Dual Trees, and Viewer Pane. However, I need to add another Tree. How would I do this? (I could drop the Viewer pane if needed).
A third folder tree??
Correct.
I use the first folder tree and display as "reference", the second tree and display as my "working set". When I find files in the "working set" that matches my "reference", I would like to move them to a 3rd location in the 3rd folder tree.
I guess that makes sense. Can't be done in a single window, though. You'd have to open a second window and have it on the side.
OK. I thought that it was possible to actually add components to the lister, such as an extra display, tree etc. It must have been in another filemanager 
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If I open a second window, it does not appear to be any way of creating only a tree. I must, at a minimum, have both a tree and a display?
That's right, unless you open just a file display and put it in Flat View (Grouped), with all files hidden. (But then all the folders will always be expanded, which I doubt will be very useful in this case.)
That's two trees (and two file displays) the same as Opus can do, not three trees.
I think we can all guess what three trees look like though. 
