Re: [ELPA] Brief v5.90: neighboring window merge on deletion

[martin rudalics]

>> IIUC handling overlays with a 'window' property with current means is
>> much too cumbersome.  One would have to investigate all overlays in the
>> window's buffer and duplicate them if they have a 'window' property that
>> references the cloned window.  In practice, most overlays don't have
>> such a property.
>
> But crucially, the overlay that implements region highlighting does.

This, cursor face highlighting and rectangle overlays are special.  They
change with the selected window, the region and/or the position of point
and must be regenerated in every redisplay cycle anyway.  Which means
that they need no special attention when cloning a frame or window
configuration.  Others, like the one used by 'hl-line-mode' are handled
via a post command hook and probably need no special attention either.

The overlays used by 'compare-windows-highlight' or
'isearch-lazy-highlight-match' seem more sensitive in this regard.  I
doubt that they would survive a change where windows do not preserve
their identity.

martin