Re: visual-region-mode?

[Juri Linkov]

> I don't think there can currently be multiple regions at the same time.

Multiple regions are already supported - rectangle region is
one implementation of non-contiguous regions.  So you can define
your own region shape by extending region-extract-function and
redisplay-highlight-region-function to e.g. put region boundaries
at positions of marks from mark-ring where C-SPC will add more parts
to the region.

> As for doing other things, like replacing text in multiple parts of a
> buffer, is that something that could be usefully done with indirect
> buffers?  With multiple regions, I'd highlight some parts of the buffer,
> do the replacement limited to these parts and would be done with it.
> I'd be able to see all of the buffer while doing this.

query-replace already supports multiple regions.