Re: History for query replace pairs

[Juri Linkov]

> - You still have access to the "TO-history" in the FROM case, indirectly
>   (by browsing the corresponding FROM/TO pair and erasing the FROM and
>   the separator).

The only problematic part is that if the user will be able
to erase the separator, then the user rightfully might want
to insert it back, but it's not straightforward to type a string
with text properties.

OTOH, it should be easy for the user to kill/yank the TO-string
to the FROM-field without erasing the separator that could be
marked as read-only exactly like the minibuffer prompt.

Perhaps using the Widget library is too heavy to implement this,
so it should be possible to have two fields in the minibuffer
by putting the properties `field' and `read-only' on the separator.