Re: Emphasizing the top of the frame

[martin rudalics]

> The TTY display code is frame-based, and for a good reason.  IOW, it
> updates the entire frame, not each window separately.

But for that it (1) has to "walk the window tree as well" and (2) know
where to draw the minibuffer window.

>> Both, a frame's root and minibuffer window, are accessible directly.
>> There is no reliance on the prev and next fields of these windows
>
> There are at least two functions in the display engine that walk the
> window tree,

Which ones are that?

> so I'm not sure what you mean by "no reliance on prev and
> next").

I meant the prev and next fields of the root window and the minibuffer
window.  The next field leading from the root window to the minibuffer
window is conceptually redundant - but might be still in use somewhere
as, for example, in ‘window-tree’.

The window tree proper is the tree rooted at the root window.  The root
window and the minibuffer window of a "normal" frame do not form a tree
- they have no common ancestor.

> That AFAIU the display engine knows that it can resize the minibuffer
> window by moving the lower edge of the root window.

All the display engine should know is that it can resize the minibuffer
up to a certain extent.  Deciding who pays for that operation and to
what extent should be left to the window code.  Think of a one line high
window bordering the minibuffer window.

martin