Re: MY window tree!

["Lennart Borgman (gmail)" <lennart.borgman@gmail.com>]

martin rudalics wrote:
>  > I have actually changed that to just change the 'window property of the
>  > overlays. No overlays are normally copied any more. If the window object
>  > that the 'window properties points to is not a valid window any more
>  > then I just replace that value with a pointer to the new window that
>  > have replaced the old one.
> 
> I'm using this concept for two years now and it never failed (I suppose
> because a window can't be collected as long as an overlay references
> it).
> 
>  > I guess that for most cases this will be sufficient. But there can still
>  > be cases where a mode (or some other code) have a persisting pointer to
>  > a window object. I can not replace this pointers.
> 
> Never mind.  `window-configuration-change-hook' must handle this.  Any
> mode referencing a window object must be aware of the fact that the user
> may delete the window and recreate another one showing the same buffer
> whenever she wants to.  When one window replaces another the
> configuration changes and the mode should be able to handle this.
> 
> In some cases it might be, however, reasonable to advert the mode that
> the window has been resurrected.  Hence, what's needed are two hooks: A
> `before-winsav' or so hook (which tells the mode designer to not run any
> configuration change hooks) and an `after-winsav' hook.  The latter
> would have to be called with a list of old-window/new-window
> correspondences (again I suppose that windows are not collected as long
> as they are referenced from that list).


Ok, now I see what you mean with the hooks. I will add it in a minute.

But there is one thing I do not understand. "Collected" above is that 
garbage collected? Do you mean that the window object is available and 
not garbage collected until some time after all elisp pointers to it are 
gone?

How does window-live-p fit into this? The doc string a bit cryptic says

   Returns t if object is a window which is currently visible.

Is an invisible window object a window that has elisp pointers to it, 
but is not on any frame? (And can never more be on any fram AFAIU.)