if I use explorer, I can drag a file from the explorer window onto another minimized explorer folder window by dragging the file to its taskbar item, which will restore that window, which in turn enables me to drop the file in the destination folder.
I know this was possible in In a previous Do12 version, but I can't do it now all of a sudden after installing 12.1.
That still works here, and is handled by Windows rather than something Opus or any individual application does itself.
Ignoring the taskbar for a moment, does drag & drop from Explorer to Opus work in general? If it doesn't, check you have not launched the whole Opus process elevated as administrator, as that would block drag & drop from non-admin apps. Use Opus's UAC support instead. (Details here.)
Yes, I can drag n drop to Opus from Explorer.
I wonder what this could be...