Here’s a dialog I already used to create a directory tree (Updated version). It just shows a normal directory tree, starting from the current folder. I had trouble implementing a good “siblings” tree, so I abandoned that - and after all, that’s your project. I’m curious to see your end result. But you could use the technique in this dialog, because the items are clickable and open the clicked folder in the lister from where the dialog was opened - I assume you will need that kind of solution too.
Furthermore, it’s an attempt to “integrate” the detached dialog with Directory Opus, in the sense that when you drag the dialog across the screen, the lister should “following the dialog”, sticking to its right edge.
Your specific treeview method would be interesting anyway. I can see how this could indeed take @Leo’s idea of prev/next siblings to a new level. If the “current position” (the current folder) would be clearly indicated in your tree view, then it should certainly be fun switching to a sibling higher up or lower down the hierarchy.
Downloads (update, v.1.1) :
AltTree_Test.opusscriptinstall (6.4 KB) - last updated Oct 25th.
Alternative Treeview Test (tri-button).dcf (702 Bytes) - Left-click to execute, right-click to edit the script.
Note: this script is just a stripped-down version of my Alternative folder selector: