When using the file browser, you can still see the top bar with tool settings. this obviously makes no sense.
- To Do
There are more cases there it does not make sense to show topbar like full screen outliner, properties...
I was working to hide and restore topbar on fullscreen (ctr+space), but I think it should be done more generic way
- Each area type (ex. SPACE_VIEW3D) should define if it needs topbar or not
- If there are no areas, that needs topbar, hide top bar
Of course I don't know how hard is this to implement :)
As far as I know only 3d view and nodes make use of top bar