I love Directory Opus, but there is something that I have always found to be a bit awkward.
When I have more tabs than can fit the screen, Directory Opus drops the tabs on the left down into an overflow menu which is on the right, leaving me sometimes looking for my lost tabs. I'm not sure if it's feasible, but I would much rather have the tabs on the right drop down to the overflow menu on the right instead of the left tabs, seeing that they're the new tabs.
Even better would be the way Mozilla Firefox handles too many tabs to fit the screen. They don't drop down at all. Once there are too many tabs, you can horizontally scroll left and right to view them.
Just a thought on improving how Directory Opus handles too many tabs to fit the screen functionality.