I know there are several threads regarding (the lack of) 3 pane view. It also seems like the development team is open to suggestions in order to creatively solve the problem. I have not read through all the threads completely (one of the threads has 100-200 comments (wow!) so I apologize if my suggestion below has already been suggested by others. Since it seems like one of the benefits of removing the 3 pane view is to conserve real estate, maybe a “pseudo” 3-pane view can be created as describe below:
“pseudo” 3-pane view: the left sidebar could be divided in sections (e.g. panes) with the top section (e.g. pane) be dedicated to a list of databases and the bottom section (e.g. pane) be dedicated to the folder view of the database that is selected in the top pane. In theory, the user could toggle between sidebar types: e.g. the current DTv3 sidebar (where you can expand each database but then requires lots of scrolling) vs having a “pseudo:” 3-pan view as just described.
Additional panes could also be created (such as favorites, smart groups, etc). This allows the flexibility of configuration (and maybe even getting rid of panes such as “favorites” if you don’t care to display them.
One of my issues with the current side bar is that it is infinitely continuous whereas the solution I just describe provides “compartmentalization” of data groups.