>> In any case
>> there's no need to scan the entire `buffer-list' for overlays. Any
>> buffer involved must have been displayed by the old window-tree and
must
>> be displayed by the new window-tree.
>
>
>
> I can not see that a buffer that the buffer must have been displayed by
> the old window-tree. The 'window property might just be there to be
> shown later when the buffer is displayed in that special window.
But where does the "special window" come from?
Case 1: The special window was created by `winsav-put-window-tree'. In
this case you set the overlay property to the special window.
Case 2: The special window was not created by `winsav-put-window-tree'.
In this case the special window must have existed before calling
`winsav-put-window-tree' and there's no need to change the value of the
property. If the property references the window it can be displayed.
Otherwise it was not displayed before and will not be afterwards.
A window property is not clairvoyant. It may reasonably reference only
a window that exists at the time you assign the property.