You can make a middle double-click open folders in new tabs.
Note: This does not affect single-clicking items. Single-clicking with the middle button always toggles a file or folder's selection, like left-clicking with Ctrl held down, unless you are using Power Mode and have configured the button to do something else.
Note: This does not affect virtual folders which Opus does not handle itself. Try in a generic directory like C:\ if it doesn't seem to work elsewhere.
Note: This does not affect the folder tree; only the file display.
See Also: Always re-use a single window instead of opening new windows
See Also: How to make Logitech Mid/Back/Forward buttons work in Opus
To make middle double-click open folders in new tabs:
Go to Settings -> File Types and edit the All Folders type. On the Events tab you can define a new Middle double-click event which runs this:
If you want the tab to open in the background, like in Firefox (at least my Firefox config ), then you can use this:
If you want to avoid opening duplicate tabs for folders that are already open in an existing tab then you can use this:
You can also combine the two:
Here's a screenshot of my setup. In my case I've got middle double-click set to open the folder in a new tab in the other side of a dual lister by adding the OPENINDUAL argument to the command.