Dynamicly add/remove sort keys was: Re: [PATCH 08/17] perf hists browser: Fix context menu item

[Arnaldo Carvalho de Melo]

Hi Namhyung,

	While continuing to process this series, I thought about one new
feature: A popup menu that would allow adding/removing sort keys, which
would entail resorting with the new sort order, what do you think?

	It may be relatively simple to implement, or I may be missing
something, this is just a brainstorm...

	To avoid reprocessing everything, which may not even be
possible (perf top case) we could mark the field as such and when
showing such hist_entries it would have a <?> marker.

	Say DSO wasn't in the sort order, then each bucket wouldn't be
for just one DSO, sure, in this case, when invoking the popup to add DSO
to the sort order, we would keep those old hist entries around but when
showing them the column for DSO would have <?>, in the top case those
would at some point decay, with the new ones with this info appearing as
time goes by.

	This is part of a general trend of removing the need to restart
the session when wanting to change the sort order, min percent, max
stack, etc, etc.

	Anyway, back to processing patches :-)

- Arnaldo