bug#19482: Changing to big font cause display problem

[martin rudalics]

>> That's confusing.  OT1H they are part of the outer window and OTOH they
>> are drawn around the window manager window.
>
> No, the border is drawn around the outer window.

Here the border appears above the title bar so it's drawn around the
window manager window.  Do you really see the external border below the
title bar?

> But if you want to span when the second monitor is connected, but constrain 
when there is only one?
> There are so many corner cases here.  There will be bug reports if Emacs 
tries to constrain stuff.
> The only one that has the full picture is the window manager, so it is its 
job, not Emacs.

Then strictly spoken `set-default-font' should not ask the window
manager to change the size of our window.

martin