At least user who has no contacts should be abe to hide "Sent" list.

Not a bad idea, but to me quite low on the priority list if we are seeking the features that will have the most efficiency impact. Need to add that I am biased towards the fastest GTD system improvements.

Well, with the current "tab style" list layout, list space is at a premium. I personally don't use these two lists, but I wouldn't care as much about hiding them if the list layout was more usable.

This improvement wouldn't make a huge difference, but it also wouldn't be all that difficult to implement. I am strongly in favor of this - in fact, it's the reason I came to the Ideas forum just now.

I love this idea. Gets back to usability... hide things that don't require my attention if I'm not using the feature. Maybe hide the tabs unless there is something actively in my list.(or simply let me turn this off...)

In the Definitions area, the user should be able to hide this 2 tabs. If I don't use them, they are just taking precious space and making me lose time looking at them.

I would definitely like to be able to remove the sent list at the very minimum, though I admit sometimes I use inbox for sorting items.
I suppose if lists were down the side, then usability wouldn't be as impacted as now.

At least Sent tab should removalble. While I never use it, it takes up the most space (the word consists of 12 characters in my language). If this tab is important to the system, at least allow the users to hide it.

Seeing as these are no longer tabs, and that the sections in the left pane are collapsible, this request is no longer valid.