I really like this - looks very professional, very considered and well-crafted! A big thumbs-up from me! :) I also agree about your colour palette - it works really well... the whole application looks like it was made by a designer and not just by a programmer... (that's a good thing, trust me!) ;)
Yes they are actually very different so we should probably have given them different names.
TAB is a toggle for hiding the current UI in the current state. Pressing TAB again, restores that state but it doesn't show all UI unless all UI was visible to begin with,
For example:
- Hide your toolbar.
- Hide your tools.
- TAB will now hide your studio, context bar, and status bar.
- Pressing TAB again will show your studio, context bar, and status bar. It does not show the toolbar, nor the tools.
- However, SHIFT+TAB will show everything including the toolbar and the tools, ignoring that they were hidden before TAB was pressed.
I hope that explains it. For the majority of people, toggling TAB is all they need. :)