bug#22104: 25.1.50; doc string of `modify-frame-parameters'

[Eli Zaretskii]

> Date: Mon, 7 Dec 2015 09:34:28 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 22104@debbugs.gnu.org
> 
> > > This part of the doc string is unclear:
> > >
> > >  Undefined PARMs are ignored, but stored in the frame's parameter list
> > >  so that 'frame-parameters' will return them.
> > >
> > > What does "ignored" mean here?  It can only mean (?) ignored by
> > > `modify-parameters', but what does that mean, operationally?
> > 
> > It means they have no effect beyond being stored in the parameter
> > list.  I will clarify that.
> 
> But I still don't understand, from that description.  What else
> does `modify-frame-parameters' ever do, besides store them in the
> parameter list?

Quite a few parameters require modify-frame-parameters to call some
API in order to put the parameter in effect.  For example,
background-color -- just storing the new value won't magically change
the color, would it?

IOW, modify-frame-parameters is not just for altering the params
alist, it is primarily for changing the frame according to the changed
parameters; it records the parameters in effect in the alist mostly as
a side effect.

Yes, "modify the frame parameters" is ambiguous.