RE: binding c-h in isearch

[Drew Adams]

> > bind C-h to `isearch-mode-help'.
> 
> I like the simplicity of it, indeed.  But I also agree that 
> C-h k during isearch would come in handy sometimes, so it is
> a good idea to try and make it work.

That's a very minor advantage. And with the conventional approach, you would
have that info anyway, once you have displayed the isearch-mode help, at the
cost of an extra key hit or two. With the conventional approach, you would see
succinct help about _only_ isearch mode, and you could always drill down for
more detailed info if you want.

The proposed approach, besides making the UI less conventional and so more
complex, will make you wade through the other global C-h crap (either an extra
prompt or the complete C-h C-h display) to get to whatever might be specific to
isearch mode. The same is true even if we show the C-h m display instead of the
C-h C-h display: it contains stuff that is extraneous to isearch.

IOW, either you want (truly) global help (what RMS asked for) or you want
isearch-mode help. The proposed approach gives you something halfway between.
And it's not even obvious (esp. to newbies) that it does that - you might think
that you're seeing vanilla global help, not help tailored for a particular mode.

[Yes, that can be true for other modes too, but isearch-mode is a bit peculiar.
It is not a conventional minor mode. You cannot do M-x isearch-mode to enter
isearch minor mode - isearch-mode is not even a command (and isearch-minor-mode
doesn't even exist). And if you do M-: (isearch-mode t), the top of the help
buffer says "isearch-forward is...", not "isearch-mode is...".]