bug#16923: 24.3.50; reression: `set-frame-size' loses mode line

[martin rudalics]

>> And it has a mode line and you switch to another Info node and you want
>> to adjust the frame to the size of its page but in fact the page size
>> did not change but the mode line disappears?
>
> I'm not sure what the question is.

It was an attempt to describe what happened.

> But yes, except for the last part.
>
> It is not the case in general that the page size does not change when
> the mode line disappears. IOW, I think you are guessing that the newly
> visited node has the same page size as the last-visited one, whenever
> the mode line disappears. That is not the case.  IOW2: Frame resizing
> may well change the frame size when the mode line disappears.
>
> I see no connection between the occurrence of losing the mode line
> and whether or not frame fitting actually changes the frame size.
> And in any case, even when the size might end up being exactly the
> same, `set-frame-size' is called.

`set-frame-size' returns earlier when no change of the size is called
for.  But if you say that it does not depend on whether a size change
occurred there's no sense pursuing this track any further.

Anyway - the two puzzling aspects are that the mode line apparently gets
erased (who can do such a thing to the mode line?) while the header line
remains unharmed.

martin