Folders vs Groups (virtual folder / workspace)

There seems to be two key areas of the "side bar". Active files (open), and Project files. Active files are under "Files" or "Group #", and Project files are under "Folders".

I feel that "Files" are a bit redundant when you have tabs. What would be better is a "virtual workspace" of files/folders that aren't open. Basically have a "Group" that is a "virtual folder" that contains references to other files/folders. If the side bar looked like this (https://github.com/jezdez/textmate-missingdrawer) you could give actual folders a blue icon and groups a yellow icon.

The side bar would essentially be what's under "Folders" (with a different look). You can add physical folders to the project. When you add a "Group" they are mixed in with top-level folders with a yellow folder icon. You can drag other folders/sub-folders/files into a group and have it copy those references.

The reason behind this is "Groups" are a temporary workspace that can be easily removed (delete key deletes reference without asking). "Folders" are permanent parts of your project (delete asks you if you want to delete the actual file). With "top-level" folders you can either delete the actual folder or reference.

I know some others may actually prefer having "active files" in a side bar instead of tabs. This should be a different stackable panel.

With the tabs themselves, would be nice if they worked like Firefox's tabs (don't squish tabs too much, they fall off at some point and arrows appear, and a menu is on the right side to see all tabs).