RE: RFC: Flavors - naming significant sets of customizations

[Drew Adams <drew.adams@oracle.com>]

> > However, themes are not very 'hygienic' -- you cannot easily roll back a
> > whole theme; when you choose a new theme, it works on top of the already
> > chosen theme, with all the non-overridden settings still active.
> 
> Maybe I don't understand, but it sounds like a bug.

It is.  Bug ##15687:
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15687

> Or maybe a mis-use: custom themes *can* be stacked, so if you want to
> replace a previous theme with a new one, then you need to remove the old
> and add the new one.  Maybe the UI needs some work to make it more clear
> (and make it easier to switch between themes).

The bug is not the fact that you can accumulate the effects of multiple
custom themes.  The bug is the fact that you cannot restore the state of
Emacs before any theme was applied.  There is no way to take a snapshot
of Emacs before theming and then restore to that.

You can add themes, for a cumulative effect, or you can replace the use
of one theme by another, but you cannot undo a theme, i.e., you cannot
untheme.

Such undoing was, and still is, trivial to accomplish with color themes:
http://www.nongnu.org/color-theme/.

This is the main reason that it is wrong to think of Emacs custom themes
as replacing color themes or, as is commonly stated, the former make the
latter obsolete.  So far, each has some advantages over the other.