I mistakenly selected "Open in opus" on the context menu of the recycle bin instead of "Empty recycle bin" and now when I double click the desktop, it opens a single pane lister with no folder tree and the contents of the recycle bin. 
Any idea if and what setting will fix this?
I have recently upgraded from 
10 to 11 and finding quirks that were not there in 10...
thanks for any help
Your Opus must be configured to automatically update the default lister whenever a window is closed. (For what it's worth, the setting is very old and not new in Opus 11, but maybe you're using the default configuration now and forgot about changing it a long time in the past in your old config.)
The Startup Folders FAQ has a quick step-by-step on what to do.
I am having this same error and it's not fixed by the link you sent.
In my case, whenever I open the recycle bin, if it's the only open lister at the time, then close it, from then on when I do the double-click to open the new lister it opens the empty recycle bin (which is not the problem), but also has lost my dual pane view and it becomes a single pane with no left column for navigation. To fix it, I have to select the LISTER STYLES dropdown and select DUAL PANE, even though it's already set to that in the drop-down.
This is VERY inconvenient, and has been happening since I moved to DOPUS 11 almost a year ago. I had not ever had this happen in the older DO 10 versions. That doesn't mean the error didn't exist, I just never had it happen. I do have the default set to open the last pane after a close, because that's the way I need it to act. I just don't want it to "forget" that it's in dual pane mode when I restart it and not leave me an easy way to get back to normal operation. Changing it to always open in the same location would mask the error but would not fix the problem and would not operate in the manner that I need DOPUS to function.
Currently the only way to keep this from happening is to have another lister open before I double-click on the recycle bin that stays open after I close the recycle bin.
As a temporary work around, is there a way to exclude the recycle bin from using DOPUS without completely removing DOPUS from replacing the default file manager in all other respects?
Brian
Select Preferences / Launching Opus / Explorer Replacement / Replace Explorer for all file system folders (recommended) and Opus should no longer handle double-clicks on the Recycle Bin.
You can also add it to the exclusion list in the same dialog, if you want to use one of the other options, but the recommended option is usually best and easiest.
Alternatively, you might want to turn on: Preferences / Launching Opus / Explorer Replacement / Open all Default Lister tabs when opening a new window (and the parent option to open folders in new tabs).