Re: question about frame local variable

[Gerd Moellmann]

Kenichi Handa <address@hidden> writes:

> CCed to Gerd.
> 
> In article <address@hidden>, Kenichi Handa <address@hidden> writes:
> > Ideally, I think selecte-frame should change the value of
> > Vscalable_fonts_allowed when that has frame local binding.
> > Then, C code can simply refer to this variable to get the
> > current value.
> 
> I found that the above is not enough.  It seems that the
> display engine doesn't issue select-frame; i.e. provided
> that there are two frames A and B, there is a case that the
> display engine redisplays A while the selected frame is B.
> 
> It means that even if we make such variables frame local
> that affect the redisplaying (font-selection, etc), any
> frame local bindings are just ignored.
> 
> Gerd, do you remember this matter?  Is my analysis correct?

I think so; it matches what I remember.  Local bindings are not
supported for all redisplay variables.  AFAIR, that has always 
been the case and isn't new in 21.  Where it is supported,
I think redisplay looks at frame parameters.

(BTW, calling select-frame in redisplay would almost certainly not be
the right thing to do, which probably gets obvious when taking a look
at what that function does.)